# Plants out competing algae-does this really make sense to you?



## yoink (Apr 21, 2005)

I think it's mostly about ammonia levels triggering algae. Enough plants growing well will suck up any/all ammonia leaving no trace amounts of ammonia set the algae off.


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## plantbrain (Dec 15, 2003)

Light would be about the only one I can think of.
Perhaps NH4 and CO2 for certain species of algae.

Regards, 
Tom Barr


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## scolley (Apr 4, 2004)

chiahead - IMO you have asked an outstanding question, that deserves full discussion. I, for one, could not be more interested.

I am no expert, but I have been paying gawd-awful attention for that last few years, and am personally convinced that any language about "_out competing_" algae is total cr*p and harmful to the hobby.

I am willing to stake any "reputation points" that I have earned that high order plant cannot "_out compete_" lower order algae. Algae will kick plant's a** every time algae decides to truly go head to head with plants. I DO NOT believe that higher order plants can suck nutrients out of the water column faster than algae can use it. That's what the term "_out competing_" implies, that IMO is mythology and is a total crock.

I do believe instead it has NOTHING to do with direct competition, but is instead the management of trigger conditions. As yoink mentioned earlier, with regard to ammonia, and Tom Barr has stated many times with regard to that same effect.

Bottom line - IMO plants cannot usually "_out compete_" algae. But they definately can retard the triggers that causes algae to grow, ammonia being the primary trigger.


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## chiahead (Dec 5, 2005)

plantbrain said:


> Light would be about the only one I can think of.
> Perhaps NH4 and CO2 for certain species of algae.
> 
> Regards,
> Tom Barr



ya one might think this but I recently(3 weeks ago) switched my 24g nano cube from 2x36w PC to a 150w metal halide. Algae grow has all but dissapeared. I was mainly dealing with BBA and some hair algae. My occasional cloudy/greenish water also dissapeared. I did not change my dosing or fish load at all. The nano tank I have has nothing but slow growers in it like Ammania Bonsai, hair grass, HC, and anubias nana petite. Co2 has always been through the roof on this setup 60ppm last time I checked. 

I personally think its a combination of a few things. First the tank has to be in balance, ferts, lights, plants, filtration, etc. Secondly I do believe that some plants can produce an algae deterant of some kind. Kinda like when I was getting BBA badly. Some plants just didnt have it and others were covered, why? Water movement was good and some plants were right nex to the other. Same thing with hair algae or staghorn algae. I am not saying that all plants can do this but I think if the tank is in balance and they are growing well then this can happen. I am by no means a scientist of any kinds nor do I clkaim to have even half the answers here. I just never understood this comment made by so many. This is the most common response to newbies just starting out also. Maybe its a phase like limiting Po4 was a while back. OK I will shut up now I am rambling a bit.


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## scolley (Apr 4, 2004)

Now that I've dropped the gauntlet on this topic, I suppose I should be completely clear about my position...

Algae can be overcome in any one of four ways, or a combination thereof:

1) *Starve it *- you can deprive it of nutrients (or light) and keep it from growing. This will also kill plants, but possibly not as quickly because plants have better reserves. That's one strategy.

2) *Eat it *- algae grows exponentially. One becomes two, becomes four, then eight, then 16, then 32. Pretty quickly this turns into big numbers. Various cleanup animals - Amano shrimp, oto cats, SAE's, and a host of other planted tank familiars, can help keep the quantity of algae down to a level that it can't be seen. But remove the cleanup animals, and the math can take over fast - and so can the algae.

3) *Don't tell it to grow* - these are the triggers. Most commonly identified as ammonia or NH4, there appears to be chemical signals that tell the algae "now is a good time to explode!" Removing those triggers is probably the most successful single method of combating algae.

4) *Poison it *- I'm not going to go into that here, only becuase most methods also poison plants.


Using the first three of these methods together is, I suspect, the most effective algae fighting strategy of all.

But what about "Out competing"? What about growing so vigorously that algae doesn't have a chance?​
IMO that phrase, "_out competing_", should be removed from the planted tank lexicon with respect to algae. You can't "_out compete_" it.


If its growth is triggered, and if nothing eats is, and if it has nutrients (and light) long enough, no amount of healthy plants in the world is going to hold algae growth back. You have to eat it, starve it, or deprive it of its growth triggers.

Anything else is a losing game.​

So the phrase "out compete" is a misnomer, and we should all stop using it.


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## chiahead (Dec 5, 2005)

Nh4 triggers algae to grow in what way? I am confused on that issue also?


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## Brilliant (Apr 11, 2006)

I think there are different types of algae and this suggestion is a safe generalization to keep tanks algae free.

About the competing thing...I think if your plants are growing "like gangbusters" then the algae doesnt get the little things it needs because the plants suck em up fast.

I dont know how to explain this but once I started fueling my plants with nitrate the damn algae went away. Ive always doubted the adding nutrients and algae goes away thought but sure enough...here I am adding nutrients and my algae is going away. 

I used to have a cloud atop my sunsets now they are shining.


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## distrbd (Feb 17, 2006)

SCOLLEY:
2) Eat it - algae grows exponentially. One becomes two, becomes four, then eight, then 16, then 32. Pretty quickly this turns into big numbers
4) Poison it - I'm not going to go into that here, only because most methods also poison plants.



Great discussion.In my experience only 2 of your 4 steps would be be most effective in reducing algae growth.
1:reduce lighting
2: achieve zero ammonia
the other 2 steps do not work as well in a big tank ,as you said,you can't poison without killing the plants .
But IMO you can not have algae eating fish and snails and to combat the growth of algae unless your whole tank is stocked with these creatures,I am talking about a 100g or bigger tanks.
what I 'd like to know is what conditions trigger Ammonia in a CLEAN tank?
it is easy enough to play around with amount of light getting to the tank but there has to be afew easy straight forward steps to control Ammonia spikes.


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## scolley (Apr 4, 2004)

No time to get into this at the moment, getting ready for vacation...

But there is one area where plants "out competing" algae is possible, and that is with plants actually producing chemical algal inhibitors. And while on one hand I know this does indeed occur, and there is some level of understood science around it, I do not believe this is what's going on (to any significant extent) when we dump a bunch of plants into a tank to fight algae.

There are, of course, a few plants that are exceptions to this, like hygro I believe, that are known to have algae inhibiting abilities.

At the end of the day, I think it typically gets down to one or more of the four things I mentioned earlier - with true "plant to algae competition" being quite the exception.


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## plantbrain (Dec 15, 2003)

Take a cleared field.

Now leave 1/2 empty
The other 1/2, plant lots of trees

Eventually, maybe 100-200 years, the trees will take over the other 1/2.
But if you only plant a few trees on the tree side, the weeds will invade, but over time, the forest will form and force the weeds out.

So as long as the fiorest has what it needs, good ample water, nutrients, no fire etc, the forest will eventually dominate.

The time scale is much shorter in our tanks, but the idea is very similar.
Plants grow and take a long time to estblished, algae? A few days.

If you plant heavy and lots of trees right away(the same is true for ag crops), few weeds will invade.

The Trees block much of the light(not all obviously).
Light is pretty variable and critical in aquatic systems.

Floating plants obviously block the light and are often the dominate plants in aquatic systems.

Submersed plants form where the floating plants cannot and can live at lower light levels.

In an aquatic system that's stable, CO2 is good, nutrients are good and light is good. As the biomass builds up, the amount of NH4 is reduced and very small.

Now what happens when the system is messed with?
Say CO2 drops due to excess plant growth or low circulation/stagnant water?
Or the turbidity of the water goes way up and blocks all the light?
Or there isa huge spring rain and snow melt and all the nutrients and dirt, NH4washes into the stream?

Algae are well adapted to this, they have many sexual stages, in general, algae plants are reproduced by vegetative methods, seldom sexual ones in a stable system. Annual aquatic plants are well adapted to droughts and where the water dries up and then new rains come.

Much like most annuals(desert plants).

Aquatic plants have a specific niche as do algae.
Each time scale and change in the season can define such a niche.

We often mess with the CO2 all oveer the plant, do not add enough plants from day one, then don't add enough nutrients to grow the plants.

If you add lots of plants from day one, add nutrients, stable CO2 light, prune and maintain the same biomass, things do go well.

You have provided an ideal niche to grow plants.
If not, you will get algae.

Which type of algae depends on what niche you provide.
There are springs in Florida dating back 500 years(Ponce De Leon's Friar wrote accounts of them) that have been nicely fully planted and still are today. They are stable, nutrient rich, good CO2, and fully planted.

Regards, 
Tom Barr


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## BlueRam (Sep 21, 2004)

I agree with Tom.

My own idea is that algea grows in 2D (exception greenwater) and plants grow in 3D so the plants can grow over the algea an block light.

If this was true algea would be most visible on plant fre areas like A) the glass and B) old leaves/hardscape.


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## LS6 Tommy (May 13, 2006)

I stopped all dosing in my tank for a full week when I was on vacation. I din't reduce lighting or CO2. When I came home. The plants looked great. Any algae I had was almost gone, with the notable exception to the GDA on my glass, but that had almost run its course. I do had some darker hard green algae on some of my slower growing annubias, but that's always been the case. I'm trying backing off on my dosing for a while to see what happens.

Tommy


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## plantbrain (Dec 15, 2003)

Some folks make claims, (they are wrong), about allelopathy being a mechanism. Even if it occurred, it's going to be very subtle.
To date, not one study has ever shown it to occur in a natural system with submersed aquatic plants.

There are studies where they take some extract, crush a plant up, put some highly concentrated "juice" in a test well with various organisms, such as some species of algae(not the ones typically we deal with) and they see if anything happens.

Hardly the same as in situ testing from the living plants/algae.
so this is nothing like our tanks and the plants, unless you crush your plants and add the plant juice in very large amounts

In terrestrial allelopathy research, where it does occur in the root zone(not the leaves), one of the methods used as a "control" is adding activatred carbon to the soil/divisions between the plants of interest.

Activated carbon will remove the organics such as allelopathic chemicals rapidly. Likewise, in aquatic systems, using AC in the filter is a common practice in the hobby.

So.......
If you accept the allelopathy hypothesis......then AC would induce an algae bloom since plants are adding these anti algae chemicals(that is the assumption).

No allelopathic chemicals to stop the algae=> algae bloom.

Also, while the plants may not be doing this, perhaps fungi or bacteria might, still, even in that case, the chemicals would still be removed.

Large water changes, say daily 80% would be removing the allelopathic chemicals as well(not all, but a lot of it), and should induce some algae if you accept this hypothesis.

Adding large frequent water changes and removing organics helps plants grow better in the observations, not hurt them and does not induce algae blooms.

I've added NH4 daily at about .4ppm, then done 80-90% water changes=> no algae.

If I wait 2 days, I get algae.
If I add Jobes sticks to the water column, I get algae blooms, if I change the CO2 all over, I get algae.

CO2 variation seems to induce certain species of algae as well.
Algae have sexual stages and these respond like a seed responds to warming trends/spring wet rains.

But they respond to NH4, CO2 changes, perhaps low O2(not high O2, I've already looked into that) etc.

Why algae grow is much more speculative.
But..........what does not cause them to grow is easier to prove.

Adding lots of NO3, say 100ppm or more, did not induce any algae
Adding lots of PO4, say 5ppm, did not induce any algae
Addign lots of Fe, say 5 ppm did not induce any algae
Ca, Mg, SO4, K+, Cl-, have enormous wide ranges folks maintain and wide number of plants, no algae as well.

Now what about too little?
Oh, you know the plants are hurting, but the algae have no issues.
Much like trying to starve a mouse to save an elephant. 

Algae will grow on plant leaves, but if the plants grow fast enough to outpace the algae, the algae will be blocked from the light as new plant growth above blocks the light reaching older leaves.

As long as the plants have enough nutrients to maintain a fast growth rate, they will out pace the algae. Algae backs off because they can wait till things run down and the plants slow/die back some before making their move(CO2 variation/NH4/light increases etc)

I think way too many hobbyists see correlation and think it = causation, this is not true and causes a lot of myths on this subject in particular.

Time frames also are important.
Many stop dosing and test etc, but few calibrate their test, few have no fish at all, plenty of mulm built up in the substrate or other potential siources and plants often have reserves for a fair amount of time, often 2-3 weeks and some species do better than others.

The other issue is reference, compared to what?
Some folks are fine with some easy plants and a tad of algae, not much pearling etc. Some are very picky and want total pearling most of the light cycle, rapid healthy growth etc.

You also need to be able to have mastery of CO2, NO3, PO4, each and every component, not just some. This is huge challenge for most folks.
I don't need to master them all the time, just long enought o do a 3-6 week test run abnd vary one of interest.
Then go back and repeated it again, then start with a new element/nutrient.
You also need to start with a healthy tank, not one with an on going algae problem that's existed for some time.

Many hobby assume things are fine when they are not and are lead to believe incorrect notions. Exploring each nutrient over a wide range individually is very useful. From very limiting/algae blooms etc, to extremely high to where shrimp start dying off.

CO2 is also preferred by algae also, not many try and limit that for some reason:icon_roll 
Same deal with ligth.

Many add nuke power to their lighting systems thinking more is better, same with CO2, but when it comes to nutrients?
Suddenly they want to rewrite the rules of plant science and proscribe their own agenda of how the world is suppose to work according to them, even attacking me and suggesting I'm closed minded and not open to these "new and novel methods for growing plants"

That's the same argument and method used by Creationist, Scientologist and Aqua-schisters. "Here are our conclusions, let's see what facts we can find to support them.......anyone that disagrees with us we will poo poo, sue, smear and tell people they are just not nice rather than based on tbe merits of the issue" 

Science makes observations, test some hypothesis, and sees what conclusions can be made based on those findings.

Rather than using the "There's so much we do not yet know" cop out, why not suggest something that is known to solve the so called mystery?
If you really believe it's some "new thing" that no one in aquatic botany, agricultural science and Phycology is yet to be aware of, then make a hypothesis and then test it to see if it's correct.

Discussion is good, taking things personally, laziness+loquiousness and not doing your homework are bad.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

The references suggested for allelopathy in DW's book are mainly all of the type that are crushed extracts at extreme concentration. I do not find the table of much use/utility, it's speculation and no meat.
A few test(AC and water changes etc) can show that the mechanism does not act in a significant manner, certainly not one worthy of serious discussion on this issue, and the science also suggest it does not occur in any significant manner in natural systems as well.
That does not mean it cannot occur, it just means that it's very unlikely and I've not seem anything I can attribute to it either havign played with AC and large water changes.

You also must over come similar effects by all 300 species of aquatic plants and each chemical extruded from each plant having the similar intensity of anti algae suppression.

What are the odds that all 100-300 species of plants kept in aquariums have the same chemicals, or the same intensity of algae supression at both high and low biomasses under a wide range of parameters?

Those odds are so low, you'd better go play lotto.

I think these 3-4 things really put the nail in the coffin for the allelopathy hypothesis.

Regards, 
Tom Barr


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## SCMurphy (Oct 21, 2003)

scolley said:


> So the phrase "out compete" is a misnomer, and we should all stop using it.


Actually it is an accurate statement, if you consider shear biomass. The small levels of nutrients which *can* grow algae *won't* support a large biomass of algae. Meanwhile plants are joyfully sucking up all that's available to them, and recycling most of what they have already obtained. When algae dies, decomposes, and releases nutrients it is not recycled internally like in plants. It is released and some goes to plants and some goes to algae, keep up the cycle and eventually enough ends up in plants that the algae is 'out competed'. Useful and accurate statement.


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## plantbrain (Dec 15, 2003)

If it where perhaps a closed system, which obviously it's not since folks do water changes, add food, fertilizers, prune and remove plant biomass etc and what not. 

The algae never where limited by any nutrient in a planted tank even if the biomass was 1,000,000,000 times more.

Both the plant biomass and the algae biomass still have the same access to 2ppm of PO4 in the water column and folks can dose and maintain 2-3ppm of PO4 so the PO4 is never limiting for either species/group of autotrophes.

What is preventing the plants from limiting themselves?
Good nutrient levels.

Algae need even less.
So obviously they cannot be limited by nutrients really.
Adding 50ppm of NO3 and 3 ppm of PO4 is certainly non limiting for both groups of competitors.

Other than perhaps algal germination inducers like NH4/CO2 variations.......I don't see any evidence that plants compete directly for any nutrients, light I'd say is the best thing if I where to pick one, and maybe NH4.


Regards, 
Tom Barr


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## guaiac_boy (Nov 5, 2005)

May I ask the interested parties to reduce this into practial terms, i.e. what are the key points to establishing and maintaining an algae-free (or almost algae-free) aquarium?

I'll propose a few ideas. I'm open to all suggestions & input......

1) start off with a large plant mass - I'm not exactly clear about why this should help, but it seems to.

2) keep ferts at high enough levels to prevent deficiencies in the plants.

3) keep CO2 high enough to keep plants happy and keep it stable.

4) don't overstock the tank.

5) don't overfeed.

6) don't disturb the substrate too much.

7) keep intense lighting periods to 8 hours or less.

8) provide enough circulation to distribute nutrients and CO2 to the whole tank.

This same debate/discussion has taken place at many times in many different forums. I truly am interested in the science behind it, but some days, just knowing the "receipe" or even a few "general guidelines" is enough.


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## chiahead (Dec 5, 2005)

plantbrain said:


> If it where perhaps a closed system, which obviously it's not since folks do water changes, add food, fertilizers, prune and remove plant biomass etc and what not.
> 
> The algae never where limited by any nutrient in a planted tank even if the biomass was 1,000,000,000 times more.
> 
> ...



I totally agree with this. Except the light issue. I think algae doesnt need much light at all to grow. I always see it growing in both lighted and low light/shaded areas. Even in darkness. 

One idea Tom Barr if I may suggest it. The alleopathy idea, you stated that it has not been proven but if a plant does in fact produce such a thing it will in small amounts. What if the tank was full of healthy alleopathic producing plants? Maybe in combination it could help deter algae from growing? Just a thought.

I am not even too sure exactly what alleopathy is. Research time.


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## chiahead (Dec 5, 2005)

wow I just did a little research on Allelopathy. I feel like a dummy now after I know more about it. My apologies for even suggesting this.


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## plantbrain (Dec 15, 2003)

guaiac_boy said:


> May I ask the interested parties to reduce this into practial terms, i.e. what are the key points to establishing and maintaining an algae-free (or almost algae-free) aquarium?
> 
> I'll propose a few ideas. I'm open to all suggestions & input......
> 
> ...


You may want to start a new thread in that case, seems like that is really another topic.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

Chiahead, naw, don't fret there, off the cuff thinking sometimes asks some basic good old fashion questions that really are meaningful and we often think we know something about it but we really don't have the mastery we like to think.

I often find myself in that position anyway
Dumber and dumber.
The more I know, the less I know.
Answer one thing, dang, 5 more pop up.

Yes, allelopathic chemicals are produced in very small amounts they tend to be metabolically expensive and the plant better get a lot out of them.

Now it is one thing to extrude them into the soil, they are not going to go far there.

But into _the water column_?

How would a plant know how big the lake is?
The _surrounding soil is a finite thing/area/volume_.

What about streams and ribvers where the flow is unidirectional??
In a tiny pond, perhaps, but Lake Erie?

What pressures are really on the plant in large stable aquatic systems or rivers?

If they are amphibious plants, then they can live on the land and the algae are there only for awhile and then die. Not much use for such processes.

Seems more likely to see plant -plant allelopathy, rather than algae - plant interactions. 

Each time I think I have evidence of a plant plant interaction, I try and repeat it, each time I fail to reproduce each suspect.


There is not much niche overlap either.
Kinetics of uptake are radically different also.
Sexual reproduction/life histories are also radically different. 
Depth( vascular plants cannot live beyond about 10-11meters, mosses, algae can lives very deep, hundred's of meters, eg Lake Tahoe/Crater lake, the ocean for algae). Scale of their sizes are very different.

You mentioned the intensity of the chemicals:
What are the odds that each species of aquatic plant produces the same chemical/same intensity on all species of algae *but not plants?*
Note, that last part, because it would be very plausible to see some evidence of plant - plant interactions, not just algae- plant interactions.

What are the odds?
Not much, what about all 300 species of commonly kept plants?
Virtually none, you'd be more likely to win lotto.
They produce a wide array of chemicals and wide ranges of concentrations.
All of which can be removed via activated carbon.

Yet we can observe similar patterns with good plant growth and algae over all 300 species and various combinations and mixes hobbyists keep.

Healthy plants, no matter what species, tend to prevent all algae.
there are many biomass variations, nutrient levels(these I've shown to have a very wide effective range), lighting, etc.

Allelopathic chemicals are very specific, this is a far more general mechansim in terms of the observations.

So something that triggers new growth, spore germination etc is the thing that starts the algae bloom. Plants appear to do something indirectly/generally to prevent that.

NH4 we know can cause algae, so does variations with CO2.
Both would signal dramatic changes in the natural environment in aquatic ecosystems.

So those would provide a good probability of successful completion of a life history for algae, good source of nutrients, few competitors able to respond rapidly.



Regards, 
Tom Barr


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## SCMurphy (Oct 21, 2003)

plantbrain said:


> If it where perhaps a closed system, which obviously it's not since folks do water changes, add food, fertilizers, prune and remove plant biomass etc and what not.


It is a closed system inbetween these events. Doesn't have to be a black box, semi-closed is enough.


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## Bert H (Dec 15, 2003)

> NH4 we know can cause algae, so does variations with CO2.
> Both would signal dramatic changes in the natural environment in aquatic ecosystems.


Tom, I agree with these. But what about light intensity/duration as it applies to 'triggers'? IMO, one of the easiest ways to control algae is by maintaining a manageable light intensity and photoperiod. Is it a matter of the algae kicking in (being triggered) after the plants 'normal' photoperiod is exceeded in the case of having lights on for 12hours vs say 9hours? This assumes all parameters are met for plant needs. Or is there something else I am missing here?

From personal experience, cutting my lighting from 12 to 9 hours reduced some algae issues for me. They were minor, but nevertheless, the photoperiod change addressed it.

It seems to me, stability might be the key word. How often do we find minor (or major) algae issues happening when we quickly change certain parameters? Are sudden changes also considered triggers?


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## guaiac_boy (Nov 5, 2005)

Point well taken.  Sure, I'll start a new thread asking the practical application of all this. I didn't really mean to steer the converstaion away. It's just that sometimes, it seems like this topic gets brought up every couple of months, in one form or another, here or elsewhere, and the discussion is always the same. The topic is of great interest to me since the whole algae battle is probably the #1 reason that people give up on the hobby. Still, after reading through this thread, it seems like 99% of what has been said is still just theory and/or conjecture.

I agree that there is value in having the discussion, but sometimes I wonder if this is getting us anywhere. Thus, my real-world application question. I'm as confused by algae as ever. I applaud Tom's efforts to actually test his ideas -- most people lack the interest to even try. This allows him to argue from a stronger position than almost anyone else. Still, I just can't help but believe that we're still missing some pretty basic parts of the puzzle -- like two fleas standing on the back of a dog, trying to figure out how the insides of the dog work.

I look at this from a medical background, where enormous experiments are carried out over years with thousands of patients to establish the efficacy of a single idea. These studies are carefully designed and cost millions to do. On occasion, they are done well enough to allow us to ferret out some little nugget of truth.

It just seems that in this hobby reproducible, reliable data that will hold up for more than a few months is hard to come by. OK, rant over. I'll try to reign it in.

I really am interested in knowing people's thoughts about the practical application of all this.


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## plantbrain (Dec 15, 2003)

Bert H said:


> Tom, I agree with these. But what about light intensity/duration as it applies to 'triggers'? IMO, one of the easiest ways to control algae is by maintaining a manageable light intensity and photoperiod.


Generally, light in our tanks, not talking about nature here, is the same and declines over time somewhat slowly.

If those are stable, you don't have excess light , eg, the CO2.nutrients are non limiting for a given light level, then no, this should not apply.

This is a classic mistake many aquarist make, they have confounding factors, thus they have too much light and think it's their NO3 or PO4 level.

You cannot compare nutrients, NH4 etc when you have other limiting factors(CO2, NO3, too much light without also providing enough CO2 and nutrients).

That's why I chose very high light to do many of the aquarium test for EI and algae inducement test runs.

This is standard procedure.
But many aquarist have trouble providing enough CO2/nutrients at high light.

Reducing the light "magically" appears to solve the issue.
No magic about it. If you had issues with high light, you ran low on something else.

I will say that higher light, NH4 presence is more likekly to induce a green water bloom than at lower light given both are non limiting conditions and you add NH4 spikes and observe the response.

But light drives growht faster, up to a point. 
Few aquarist have max light points for most plants(450 umols is very high light, 10 cm from 5.5 w/gal w/reflectors PC lighting vs 600 umols for many plants as max light levels).
So most simply need to add more CO2/nutrients to account for higher demand driven by light.



> Is it a matter of the algae kicking in (being triggered) after the plants 'normal' photoperiod is exceeded in the case of having lights on for 12hours vs say 9hours?


I'm not sure.
10-12 hours seems fine to me.
I think what can occur is that the CO2 can be driven down and the tank runs low later in the day, or at some point due to very high light and that it causes the plants to become CO2 limited.
Algae are very fast to respond to this situation as we all know.
BBA more than others.



> This assumes all parameters are met for plant needs. Or is there something else I am missing here?
> 
> From personal experience, cutting my lighting from 12 to 9 hours reduced some algae issues for me. They were minor, but nevertheless, the photoperiod change addressed it.


I'd agree with that and would suggest some of the above to rectify it.
If you are curious, you can manipulate things and test your hypothesis.
But that involved inducing healthy algae.........IME, few if any aquarist here or on most forums are willing to do that, therefore few are sure.
Observations alone are great, but they do have serious limitations.




> It seems to me, stability might be the key word. How often do we find minor (or major) algae issues happening when we quickly change certain parameters? Are sudden changes also considered triggers?


I'd say in general, yes.
Frequent weekly water changes, even daily works well.
So do non CO2 methods where the water is not touches for months, years in some cases other than top offs.

The question becomes *which* certain parameters can be changed?

If you are adding 20ppm of CO2 at 10 hours of light at 200umols of light, then switch to 500 umols of light, I'd say there'd be a good chance of issues for many if all they changed was lighht and did not also carefully watch CO2/nutrients.

Problem is, many don't increase the CO2/nutrients etc.
Think about how the changes effect CO2, nutrients can be stabilized relatively easily with EI and not a lot of work really, so the rest is CO2.

In the springs in Florida, there is constant CO2/nutrients/Temp etc.
They are packed with plants.

The main thing that changes seasonally?
Light.

This drives more biomass growth.
Algae also.
But.......more light places more demands on CO2/nutrients etc.

You also have rain run off from the land seasonally, this runoff adds a nice spike of organic N, which bacteria go after, reducing the O2 levels and producing NH4, then NO2, NO3 etc.

So I chose the headspring where the run off is at the absolute minimum.
Still had a marked increase in Mar/April/May in algae total production as measured by Chl a. This is also when plants start growing more as well.
This is for attached algae only also(it's a spring river at the source)
GW etc may fair differently.
Lake studies are pretty good about that, warm weather triggers some to bloom in the spring, then the nutrients are sucked up all summer long and you get a clearing event/perhaps some BGA, then a Fall bloom late.
Marine algae are very sensitive to changes and temps also.
Even the full moon will trigger some marine algae to release spores etc.
My Phycology instructor at UC freaked when I correctly answered his student "question stumper", moonlight.
I got lucky I said.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

guaiac_boy said:


> It's just that sometimes, it seems like this topic gets brought up every couple of months, in one form or another, here or elsewhere, and the discussion is always the same.


Yes!!



> The topic is of great interest to me since the whole algae battle is probably the #1 reason that people give up on the hobby. Still, after reading through this thread, it seems like 99% of what has been said is still just theory and/or conjecture.


Well, you can try it yourself and see for yourself and then decide.
Theory and what you do already know can go a long way.
There are many species of algae.

So get to know one at a time very well.
That's what I did.

Then those same species are useful, because you know what and how and why they are growing.

That will tell you about the condition of the tank.

You can also take an otherwise stable tank, add treatments to it, additioons of PO4, NO3, Fe etc, over a wide range to see the effects of each individually.



> I agree that there is value in having the discussion, but sometimes I wonder if this is getting us anywhere. Thus, my real-world application question.


Sounds more like you want to know the how, rather than the why.
What does this all mean, basically?
How can this be used to help newbies?

Well, I think it already has a great deal.
15 years ago they had no clue as to why BBA grew, most said excess
NO3/PO4's etc.
BGA, GW, Staghorn, hair algae etc.



> I'm as confused by algae as ever. I applaud Tom's efforts to actually test his ideas -- most people lack the interest to even try. This allows him to argue from a stronger position than almost anyone else. Still, I just can't help but believe that we're still missing some pretty basic parts of the puzzle -- like two fleas standing on the back of a dog, trying to figure out how the insides of the dog work.
> 
> I look at this from a medical background, where enormous experiments are carried out over years with thousands of patients to establish the efficacy of a single idea. These studies are carefully designed and cost millions to do. On occasion, they are done well enough to allow us to ferret out some little nugget of truth.
> 
> ...


Well, you have how many folks looking into people' physiology?
And how many folks go into algae?
How much $$$ is spent on human science vs algae?
How many species of algae are there vs how many human species?

There is a great deal yet to be discovered, science does not know everything already, hardly. Folks seem to think it should sometimes.

There is not a lot of incentive in this field, nor $$.

Medical science?
You bet, Genetech is right down the road from me.

Few folks on campus care much about aquariums other than to grow a critter or as some lab growth chamber for a specific species.

Most are much more interested in natural systems.
I like tanks and all, but I'm more interested in nature myself too.

I like the flea analogy
15 years ago, fleas knew a lot less about that dog.

Regards, 
Tom Barr


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## vidiots (Jun 17, 2006)

I think out of human nature we try to apply a simple explanation to something that is in reality very complex. I to have been stuggling with this idea, and some things seem to confirm it while others seem to contradict it.

So far people have been discussing only the interactions between fish, plants algae and nutrients, and completely ignoring the thousands of other microscopic critters that are thriving in all our tanks. Many of these critters eat small algae keeping the amounts in check and the amount of food available keeps them in check, however relatively fewer critters can eat macro sized plants. So on this point I would agree with the plants out competing the algae, at least indirectly. However I think that algae is always present and that algae has been around longer than plants and is more adapted for winning direct competition.

As for the ammonia, many organisms find ammonia much more toxic than others. Suppose that maybe the ammonia levels kill off the critters that are ordinarily keeping the algae in check. Algae and plants both see ammonia as food, and that maybe in this case the algae begin to out compete the plants now that it's predators are gone.

I beleive that there is no such thing as a 100% algae free tank unless it was set up in a sterilized clean room and no living things were added to it and it was kept this way.

By changing our water parameters we change which living things thrive, and which don't.


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## guaiac_boy (Nov 5, 2005)

vidiots said:


> So far people have been discussing only the interactions between fish, plants algae and nutrients, and completely ignoring the thousands of other microscopic critters that are thriving in all our tanks. Many of these critters eat small algae keeping the amounts in check and the amount of food available keeps them in check, however relatively fewer critters can eat macro sized plants.


This is a very interesting point and certainly we're missing some key concepts. I've seen snail populations rise and fall at different times. I've seen hydra populations do the same thing. These are just the critters that are big enough to see. There are certainly millions of interactions that take place in our little glass worlds that we don't appreciate.


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## plantbrain (Dec 15, 2003)

Good ideas,

Bacteria are the main cycling bio organism in wetlands.........not the inverts etc, they mainly are shredders etc and function in stream ecology a fair amount. Mainly to break things down so the small organisms can get at it easier. That is the traditional view anyhow..........
One I've not been convinced of. I think that there is tight coupling between inverts, periphyton and plants, it's mainly the periphyton that is where all the cycling is. In the everglades, roughly 50% of the production is from periphyton, making is one of the very few algae/periphyton dominated ecosystems in the world. See below, there are many more references.

Such rotifers etc have been analyzed for algae control, they have some effect with things like green water, not much when it comes to periphyton really.

Fish eat these critters that are significant
http://www.blackwell-synergy.com/links/doi/10.1046/j.1365-2427.2003.01095.x/abs/

Shrimp, snails, some fish etc are already in place there.
We can see their effect.
In general, herbivores are "icing on the cake", not the main controlling factor in our tanks. The real issue is new algae growth production. Is that controlled by such micro critters? If so, which ones?

We can also remove them entirely, and see the effects of no fish/shrimp/snails etc.

Oddly, and unexpectedly, I found less algae without any critters at all, this was likely due to no available NH4 sources other than the plant leaching perhaps, some bacteria.

http://links.jstor.org/sici?sici=0012-9658(199306)74:4<1264:TABCOS>2.0.CO;2-G&size=LARGE

this would seem to contradict this paper's finding, that if you add nutrients and remove the critters, you should get more periphyton algae, this is likely due to no NH4 beeing added to my test.

Upon addition of NH4, I got algae to this same system. So there seeems to be a strong sugegstion that NH4 plays a very significant role here whereas 
NO3 does not to the same degree.

Unless it's a plant, some bacteria or algae, it's not really going to assimilate NH4. The real question is are these critters really significant or is this just some "unknown" without any suggestion that it really is meaningful to add to a mix/that will not amount to anything significant in terms of algae impacts.

I can spread doubt all day long, that solves little unless you can come to some resolve and come up with ways to get around that without having to study every single critter and spend 200 years trying to figure it out. 

The "excess PO4 does not cause algae" exmaple is a very simple test to show that it does not induce algae, and "adding NH4 does induce algae" in our systems. I did not have to study everything nor worry about these microinverts/critters etc to see the effect and the amount of NH4 added was relatively low in terms of toxicity. Who knows what their tolerances are, but I'd think they are pretty tough. 

So you need to tease apart the plant changes/algae impacts in a new tank without any micro critters vs a well established system.

We did a lot of research at UCSB in the vernal pools, the aquatic zoology folks(not me!) found that it took longer than decades for the [pools to look like natural systems, while the plants, algae bounced back very fast(a few years).

This seems to suggest that the algae/plants/bacteria can become stable relatively fast where as such smaller aquatic heterotrophes take much longer.

Loading rate of food for such micro critters is another issue for a stable population(same for plants/fish/algae/bacteria).

It gets down to this:

If you suspect a certain part of a system is significant, test it!!!
So you need to test a tank with/without these micro critters.
New sterile tanks are fine, but how long before these things start appearing and is it relly their effect or is it the bacteria? Established plants/roots etc that are causing the reduction? so the impact you see may have nothing to do or a much smaller effect than you may assume.

That's less simple.
But we could use something like labeled 15N and watch it as we enriched a tank or an algae with 15NH4 and or 15NO3.

Then you could follow the nitrogen through the system and see who gets what.

Not something a hobbyists might do
But.........there are a large number of studies where this has been done in natural and created systems.

http://www.springerlink.com/content/n2861721p4555812/

This paper is interesting about NO3 uptake.......of phytoplankton and periphyton:

http://links.jstor.org/sici?sici=0024-3590(199606)41:4<659:NUBPAP>2.0.CO;2-E&size=LARGE

It suggest that at certain times of the year, periphyton outcompetes phytoplankton, which is in line with natural observations.

Off topic but interesting nonetheless:
http://www.blackwell-synergy.com/links/doi/10.1034/j.1600-0633.2002.110106.x/full/



I think simply testing your hypothesis (rather than spreading doubt, we can always say we are not entirely sure, like that Global warming "doubt" garbage) and seeing what happens is a better approach. You learn more that way and come to better understanding of plausible causes of actions we see in the tanks, environment etc.

So figure out a way to have the micro critters both with/without, you will need to identify those that are likely the most significant players, and see how the algae production varies with their densities, NH4, toxicology. 

Snails, fish, bacteria, etc seems more likely players to me, replanting tops and removing any older leaves where such micro critters may exist(if they impact the periphyton, they will be on eht eleaves obviously) seems like you can maintain very low levels of such micro critters and we see better plant growth in those cases, not lower algae densities also.

It takes time for them to form, but it also takes time for the algae/periphyton to form. What drives the periphyton formation? Top down or bottom up trophic interactions?

Seems to be bottom up, adding NH4 induces algae, high light, low nutrients/plant deficiencies etc. CO2 variation is another thing as well.

As far as competition:
http://cat.inist.fr/?aModele=afficheN&cpsidt=2665029

This suggest what I'd said prior, macrophytes out compete algae for light.



Regards, 
Tom Barr


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## vidiots (Jun 17, 2006)

plantbrain said:


> The real issue is new algae growth production. Is that controlled by such micro critters? If so, which ones?
> 
> We can also remove them entirely, and see the effects of no fish/shrimp/snails etc.
> 
> ...


Wow Tom, those are some great links, admittedly some of them are a little above my complete comprehension level.  (It's a rough read when you have to look up every other word because biology is not my area of science)

I think that would be a very difficult thing for even you to test for. How do you eliminate the micro critters without also eliminating the organisms that they feed on? A UV sterilizer would kill both or atleast whats in the the water column, and invalidate the results of such a test. The macro critters are easy to remove, the micro ones, not so easy. The tiny ones considerably out number the larger ones and they probably respond quicker to minor changes and may have a larger impact.

I too like to test ideas, but in many cases such as this lack the means, which is why I can't get enough of reading the results of your tests. You tend to list the conditions under which your tests were conducted and that is important because what my be true under one set of conditions may not be true in another.

I could further suggest that newer tanks "may" tend to be less stable than older tanks because they simply lack the micro critter population. But, then if this were true folks using UV sterilizers periodically would have "newtank" like stability issues after each use, and I don't think that is necessarily the case.

I'm just throwing some ideas out there to support my origional point which was that these things are far too complex to be completely explained by a simple explanation. However many of us need the dumbed down version because we can't handle the complicated one.


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## plantbrain (Dec 15, 2003)

I do not think that these micro critters do cause algae to go away/stop new growth in a significant enough manner to see what we observe.

Simply trimming fast growing stem plants would remove a lot of the periphyton and the microcritters feeding on the leaves eating the algae/periphyton.

If NH4 was toxic, adding NH4 and then UV the tank there after to kill the green water would suggest algae growth would appear, but we don't see that. So that would get around the new tank issue a fair amount and could be used on a long established tank. 


A nice established filter could also be added to a new tank that has not had any critters present, eg, a non planted tank with no light, filtered tank/water etc in the dark. These microcritter herbivores would not live where there is no periphyton food source, that might be wrong, but it's unlikely.
I've done this doing other tanks over the years, the tank did well namely because of the bacteria and NH4 issues, not due to a introduction of microcritters that eat new algae.

Also, there was a UV added the end of the filter return water, not likley.....

Simply suggesting there's a lot we don't know offers little to solving anything.
People seem enamoured with this comment(not anyone in particular, but I've read it more times than I can recall) but it has little utility.

Suggesting a method or identifying things/critters in question, carefully thinking about what observations we do have already that might show a relationship, that is more helpful. Folks need solutions and methods to go about unlocking things, not unsolvable doubt and suggestions that it's too complex to understand. May as well toss in the towel and not even bother talking about it if you feel that way. That's a defeatist attitude. 

Anyone can say there's a lot we do not know even though Global warming is an accepted theory, there's always some that likes to claim otherwise. 
I've looked around at these so called microcritters/herbivores that may eat periphyton, nothing I've found looks particularly significant enough to stop algae growth on submersed plant leaves.

There's some slight evidence for this (namely rotifers) in regards to Green water.......which we know is easily induced with a NH4 dosing spike but not other species........

Nutrients and herbivores both can supress algae.
That's fairly obvious, but we know from most of the herbivores we kept that are much more significant and can impact algae to a much larger degree, they provide relatively little impacts unless the algae issue is very mild and the nutrient issues are not well balanced(eg low CO2, a little bit of BBA, adding a few SAE's knocks off what's left).

When nutrients are in good shape for the plants, very low NH4 is present, good CO2 stability ranges, plants don't get covered.

New growth shades older growth on plants where the algae would typically colonize. Plants shade plants also, we all see this.
That blocks the light getting to the algae.

At relatively low light levels we use, this slows the algae down and fair amount. This is why I said if they compete, they compete mainly for light.

See the ref's also. Typha vs Cladium and periphyton.
Same thing in our tanks. Even HC rugs are growing pretty quick, burying the older growth even though the water column is empty.

In low light tanks, there's less incidence of intense algae outbreaks, easier to maintain stable CO2, less light available for the algae to start with, low nutrient stresses for everything(NH4, PO4 etc), so it seems light is a main player here in terms of competition with more light leading to more algae and less wiggle room in a system.

Something I've maintained for a number of years and folks have long observed in the hobby.

Another thing that can kill off amny micro critters, copper(or something that targets selectively the herbivore, but not algae nor plants), that can be added, you can assay the recolonization rates for algae and for the micro inverts and see.
Copper can be added enough to kill most shrimp and inverts, and not harm the plants(aklgae has a lower tolerance to copper than plants and can and is used selectively), many species of plants are copper tolerant at higher levels, those could used to look at the interactions between microcritters and new algae growth.

Algae cultures could be added to newly treated/sterilized tanks after the copper was removed. No critters, established plants(and a plant control to make sure after effects of the copper was accounted for) and algae are present.

There are ways and the hobbyists can likely do them if they so chose and think about things. But I bet few will ever do it.


Regards, 
Tom Barr


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## hughitt1 (Jun 19, 2006)

I came across this when reading today and figured i would post it up for consideration..

from _Encyclopedia of Aquarium Plants_, Hiscock 2003, (p91)


> The best way to prevent algae in a planted aquarium is to establish continued strong plant growth. Plants have many advantages over algae when it comes to collecting nutrients and utilizing sunlight, so good plant growth will often starve algae of nutrients. The allelochemicals produced by plants may also play a part in restricting algal growth.


This doesn't really provide any great insight, and the author is certainly no expert in aquatic plant and algae interactions, but its still a somewhat authoratative view in favor of the notion that algae can be 'out-competed' by plants.

From my own experience algae tends to be moderated by the amount of plants in the tank- if i only have a few plants in a large aquarium then things can get out of hand pretty quickly whereas if i start off by planting heavily right from the get-go, rarely do i encounter any large algal blooms. Of course my little 5-gal has little planting and it does just fine as well.

If anyone is feeling adventurous and has a few extra tanks, it wouldn't be to difficult to do a makeshift experiment and setup several tanks with all things equal except amount of plant covering. You wouldn't be able to control for everything, but you could probably get an idea of how much % plant cover affect algae growth.


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## plantbrain (Dec 15, 2003)

No, I find little here, he starts off okay, plants need more nutrients and they can take them up faster, but he then says something totally wrong.

The algae are not starved for nutrients if you feed the plants nutrients.
Think about it.

You are providing *non limiting nutrients *for both the plants, and for the algae.
Not one or the other.
Starvations occurs/competition when you have a resource, nutrients being reduced down where it's limiting to one or both species.
This is not occuring here.

For the Plant competitor to out compete to exclusion which almost happens in a well run planted tank for most any visible algae species, you must provide more nutrients than the algae competitors require for good plant growth.

If we have 5 ppm of PO4 and 50ppm of NO3, clearly trhere is no way competition for N and P are occuring.

No one, not one book reference I've ever found, has suggested that the NH4 is competed for as a possible signalling while NO3 leads to reduction of new germinations of algae spores and eventually the adults die off under intense NH4 uptake. 

You can add NH4 => algae
You can add huge ranges of NO3=> no algae.

Plants also leach out a substantial and significant amount of nutrients when growing rapidly. 

As far as light, perhaps.
But, periphyton loves to grow on your plant leaves........

I have references in terms of Everglades water treatment levels for PO4.

Submersed plants can remove and grow down to about 0.050 ppm or 50ppb, algae, periphyton attached algae, about 20ppb. Phytoplankton even lower........before growth limitations occur.
Testing resolution by labs and ER companies does not get down to 10ppb effectively with a good error range.

Maybe some very very careful Unioversity Grad student might be able to tease out a decent range of P04, but many past researchers have failed to limit many species of FW algae(eg Ullrich 1989).

His comments on allelopathic chemical sounds like he just read DW's book and has not looked into more than that and the convential myth posted on the webs about algae.

I've pretty much destroyed the allelopathic idea. It's not hard and most aquarist can do that and prove it to themselves.

Think about NH4 uptake relative to both fish load and plant biomass.

Few plants=> little NH4 uptake
Lots of plants=> lots of NH4 uptake
Poor plant growth=> less NH4 uptake
Too many fish=> too much NH4 and algae grows

Why cannot we keep adding more and more fish to supply the N for the plant needs?

Think about that for awhile............

Why do we really need KNO3?
Now, you try it

I have.
I've tried the NH4 dosing
The NO3 dosing.
The adding more and more fish progressively to induce algae.

A little work and testing tells you a lot.
But most folks never do testing at all.

Just observe.
Testing will allow a lot more information to be gained.

No need to do the % coverage test for as generalization, a long way ahead of you, roughly 30-50% coverage, obviously some plant species are better than others, we have 300 species to chose from, but the 30-50% is just a general range, the more the better. Hoyer and Canfield et al suggested this amount as well.

Regards, 
Tom Barr


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## hughitt1 (Jun 19, 2006)

I Agree with your points on competition for nutrients (with the exception possibly of iron as DW points out, which may be better refered to as "differing needs", than "out-competes"). In an aquarium where plants are thriving, and algae is little to be seen, the algae _are_ being out-competed for _something_ however, be it light, trace nutrients or tender love and care from the aquarium keeper.

I Agree with you that allelopathy is not the likely culprit, however i don't think that its an unimportant factor in all cases. It may play a very subtle role in many tank settings, with certain plants or algae. I Would not however be suprised though that in certain cases it plays a much larger role. There has been some other experiments run not just using 'plant juice'. Mulderij et al., 2003 for example used filtered water from a tank with several Chara spp. and looked at its effects on several free-floating green algae (Selenastrum sp., Chlorella sp., and Scenedesmus sp.) and found that in some cases it did exhibit subtle inhibition effects (~3-7%), but had no affect on one algae.

Perhaps allelopathy plays little roles in our home aquarium, but i think its too early still to say for certain.

This is JMO though, i have no authority really to speak on this subject 

What are you studying at UCSB? I met a fellow from UCSB (philosphy department) a little while back.. school sounds very nice.

Keith


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## Hoppy (Dec 24, 2005)

Algae and aquatic plants are organisms that evolved over a long, long time to survive or thrive in their environments. A glass box wasn't one of those environments. So, when we try to guess what causes or inhibits algae, or encourages plants in preference to algae, we should keep in mind that we are dealing with an artificial environment. My understanding is that the algae we are blessed with have evolved to sit around as spores until certain water conditions are optimum for them to complete a life cycle (if they were in a natural environment). Apparently a surge in ammonia is one of the things that signal them that it is a good time to get up and start living, baby! I suspect there are other things too - like a bright sunny morning gets some of us up and at em, while an alarm clock blasting away gets others up. It could be just that simple, and not involve competing for food or avoiding certain plants secretions, etc.


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## endparenthesis (Jul 13, 2004)

Recently I had some BBA and staghorn in my tank (not a lot, but in many many many places). I let a sprig of hornwort grow in there for about a month, which quickly grew to about 1/4th the size of the aquarium volume. In the process the algae disappeared (including the algae not blocked from the light whatsoever). About a week ago I took the hornwort out, and I'm already seeing the BBA creeping back. Nothing else was done differently in that time period.

It'd be interesting to know why this happened. It seems to support the erroneous way of thinking, so I guess it's not hard to see how one could come to that old conclusion.

Suddenly there was less NH4 uptake, maybe, but that doesn't really explain why the algae first disappeared.


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## defdac (Dec 28, 2003)

> Suddenly there was less NH4 uptake, maybe, but that doesn't really explain why the algae first disappeared.


I think it does. Algae have a fast life-cycle. If you remove NH4, spores will not develop to new algae. Old algae die and there you go.


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## vidiots (Jun 17, 2006)

endparenthesis said:


> Suddenly there was less NH4 uptake, maybe, but that doesn't really explain why the algae first disappeared.





defdac said:


> I think it does. Algae have a fast life-cycle. If you remove NH4, spores will not develop to new algae. Old algae die and there you go.


Adding the Hornwort probably reduced the NH4 to the point that the trigger for the algae to grow went away. Then removing the Hornwort allowed the NH4 to climb to a point where algae was triggered to grow again.

It is my understanding that the measured residual in the water column does not accurately represent the amount of NH4 being produced or consumed, just the remainder after it is produced and consumed. If large amounts are being produced and consumed it is still readily available to plants, algae and bacteria even if the remainder is near zero. If large amounts are being produced and small amounts are being consumed you have a larger remainder and toxic conditions. If you have a small amount being produced and consumed it is not as readily available to plants, algae, and bacteria, and you probably have a small remainder. I don't think you can have a small amount produced and large amount consumed, since they can only consume what is there.


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## plantbrain (Dec 15, 2003)

hughitt1 said:


> I Agree with your points on competition for nutrients (with the exception possibly of iron as DW points out, which may be better refered to as "differing needs", than "out-competes"). In an aquarium where plants are thriving, and algae is little to be seen, the algae _are_ being out-competed for _something_ however, be it light, trace nutrients or tender love and care from the aquarium keeper.
> 
> I Agree with you that allelopathy is not the likely culprit, however i don't think that its an unimportant factor in all cases. It may play a very subtle role in many tank settings, with certain plants or algae. I Would not however be suprised though that in certain cases it plays a much larger role. There has been some other experiments run not just using 'plant juice'. Mulderij et al., 2003 for example used filtered water from a tank with several Chara spp. and looked at its effects on several free-floating green algae (Selenastrum sp., Chlorella sp., and Scenedesmus sp.) and found that in some cases it did exhibit subtle inhibition effects (~3-7%), but had no affect on one algae.
> 
> ...


If traces where an issue as she contends..................why can I add 200mls of Flourish toa 20 gallon tank and not have any issues?

Yes *200mls* at once...........to a 20 gal tank?
The water is dark tea colored BTW.........

10mls of TMG never did anything after a year.

Plenty of light/CO2, nutrients etc that algae needs............

Free foating phytoplankton really are not an issue in our tanks ever, GW is not any of those species..........

Very subtle effects, well, I can say that about scratch my left ear on Sunday's............if it's that subtle....it's not significant.
Certainly not enough to do much in our case..........Chara does seem to help in lakes and is an algae BTW....................

Algae=algae interactions is another deal..........
Adding tank water to a culture........well, that's not really practical in opur case, we have both in our tanks all the time........

I long since graduated from USCB, B.Sc. Aquatic Biology, what else? hehe
Step dad taught Philosophy at IU.

Regards, 
Tom Barr


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## hughitt1 (Jun 19, 2006)

Okay so all current research on the subject aside, what makes you so quick to rule out the role of allelopathy in the aquarium? You said its easy to prove to yourself that it is insignificant. Different plants give off different allelochemicals, so it would be unfair to assume that the results from one tank with certain plant species could be applied to the whole spectrum of possible plants kept.

If trace nutrients, and the effects of allelopathy are both unimportant, then what do you think are the most important factors in why a well-planted tank may have less algae problems than had it not been so well planted?


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## plantbrain (Dec 15, 2003)

hughitt1 said:


> Okay so all current research on the subject aside, what makes you so quick to rule out the role of allelopathy in the aquarium? You said its easy to prove to yourself that it is insignificant. Different plants give off different allelochemicals, so it would be unfair to assume that the results from one tank with certain plant species could be applied to the whole spectrum of possible plants kept.
> 
> If trace nutrients, and the effects of allelopathy are both unimportant, then what do you think are the most important factors in why a well-planted tank may have less algae problems than had it not been so well planted?


Hi,

Hehe.........
I've been at this a very long time, over a decade........
Hardly quick. I have had this same discussion hundred times maybe?

I have done allelopathy work at both the grad and UG levels with folks that actively have done research on the subject, as far as I know Diana, nor anyone has in this hobby.

Standard procedures for a control are to use activated carbon, this removes the allelopathic chemicals involved. The treatment does not have the AC, this allows the the chemicals to act on the other algae/macrophyte.

The observation is a simple thing with all 300 species of plants.
They all produce, illict the same response when grown under good conditions: no algae.

This is a widely accepted universal observation and has been by everyone for decades, not just _my own_.

Now wide ranging observations and consensus of 300 species in varying levels of densities, seems impossible that all 300 plants have the same chemical right?

Now what about do all plants also have a different chemical that has the same intensity? Likeyhood of that?

Now what about this observation.......the effect is highly significant, not a minor thing at all.

Allelopathy has NEVER been shown to occur in a natural situation after several decades of investigations. If you take an isolated test well, add an alga, then pour purified chemicals, water of a different ionic compsition, allelopathic chemicals, add highly concentrated chemicals/extracts etc, no light/CO2(or not), nutrients(did the test water added have NH4 or not?) etc there are many things that can influence the results.

And if you suggest it's very subtle, well, then it's not the mechanism acting on the algae in our tanks. It's a pretty strong stable situation.

We also see strong stable plant dominances in aquatic systems also where things like light/CO2/temp/plant biomass/nutrients are stable. 100's of years types of dominances.

And that is in a flowing river........why would such plants possess allelopathic chemicals? They would get swept down stream immediately.

There is simply little evidence to stand on here both in the observations and the research. Everything thus far has suggested no effects in the research in ecosystems.

Now if you want to get into it, set up a test and see, you may. You need to learn how to grow the algae and get it growing in log phase(again, standard procedure), often that is not done. So each replicate may have a number of subtle issues unrelated to the treatment at hand, so you often get data that might have some slight variation, but nothing significant ever.

Regards, 
Tom Barr


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## zach (May 28, 2007)

"Secondly I do believe that some plants can produce an algae deterant of some kind."

Is it not common knowledge that there is sucha thing as plant warfair, were plants try to poison other perhaps "weeker" species , and this is another reason for frequent water changes.
so i would say it is quite likely that plants have ther own algaecides.


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## ringram (Jan 19, 2005)

You're forgetting that light is a key ingredient for algae. I don't care how much Nh3 or excess nutrient is available. If there's no light, there's no algae -- explains why we do blackouts for gw and bad cases of algae, right? The more the plants grow in, the more they block the mid and lower parts of the aquarium, limiting the algae's ability to extract light, which it needs to survive.

-Ryan




chiahead said:


> (Edit)
> I just do not agree that the plants out compete anything. I do agree to have everything a plant needs at all times for them to grow properly. What is everyones thoughts on this idea?


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## plantbrain (Dec 15, 2003)

zach said:


> "Secondly I do believe that some plants can produce an algae deterant of some kind."
> 
> Is it not common knowledge that there is sucha thing as plant warfair, were plants try to poison other perhaps "weeker" species , and this is another reason for frequent water changes.
> so i would say it is quite likely that plants have ther own algaecides.


If you honestly buy that, why don't we see this effect in non CO2 systems where we go months without water changes and can add activatred carbon to remove these so called inhibitors?

Easy test to do.

We do water changes to remove excess, add ferts to prevent deficiencies.
You can fiddle and test each thing and dose without doing water changes also. Plants do not die.

Just because you might want to believe something certainly does not make it so.

We can easily add activated carbon, which would selectively remove such compounds and never need to do water changes based on the assumption you make.

Water changes have little to do with this issue, that's more a management issue for balancing nutrient levels and getting rid of dirt/mulm etc and to clean the tank easier.



Regards, 
Tom Barr


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