# Algae and Nutrient Deficiencies



## aqenthusiast (May 12, 2012)

Very much appreciate the effort and content zapins.. Very useful to "non-botany" people like me to understand why of algae and what approach can be taken. .


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## Monster Fish (Mar 15, 2011)

Great writeup. After doing dirt tanks for a few years now, I've noticed that algae only appeared in the tanks during the initial startup (which is negated with frequent water changes and adding a lot of floaters and weedy stems) and when the dirt starts to lose its nutrient content after a few years. In between, plant density is heavy. Floaters clog up the surface of the tank and develop long roots. The root feeders have become weeds. Any algae such as staghorn and hair algae is nowhere to be found. BGA might be present but in small quantities, usually at the output of the filter. After a year or two, the plants start looking bad and the algae starts to take over. At that point, it's best to start over with some fresh dirt. 

As for the BBA being caused by organics, I read all 40 something pages of that thread on APC which talked about how dissolved organics in the water was utilized by algae. I believe it's true from what I've seen. Slow growing plants with damaged leaves become bba magnets. Anubias, ferns, and slower growing crypts are the most susceptible in my tanks. These are in low tech, non-co2 injected tanks btw. The bba never shows up on the newer leaves. Changing the water more frequently in larger volumes helped prevent new outbreaks of bba. But the old tufts would still remain. The best course of action at that point was to trim any of the heavily infested leaves. There's no point in using H2O2 to spot dose when you can just let the plant grow new leaves. The 1-2 punch works just fine IME but if the plants aren't growing well, the bba is gonna come back unless you improve your plant growth. Just my two cents.


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## plantbrain (Dec 15, 2003)

Good conclusion.

Allelopathy might be an issue of "here's the conclusion, let's see what facts we can find to support them."
It be unlikely true in flowing systems as the chemicals are quickly and immediately washed away, and that's the lion's share of the systems in springs in Florida. How does a plant know how large the area is and what the water flow is and how much to produce?
How is it that we see the same observations in some 400+ species of aquatic plants? Surly, all 400 different wide ranging species do not all produce some secret bullet chemical?
Those odds are well over Billion's to one.

Ole beats the rest of that argument to death:
http://www.bio-web.dk/ole_pedersen/pdf/TAG_2002_15_7.pdf

Water changes are a very easy way to remove allelopathic chemicals.
If that's not good enough, they no water changes should kill off any algae, but clearly that does not work, the opposite tends to be more true for cO2 enriched systems.
And you can use activated carbon which is a standard control for allelopathy research studies in plant ecology. Plenty of hobbyists have used AC in planted tanks for years, no one has noticed any increase in algae with it's use. To accept the hypothesis, you would almost need to have most folks see algae blooms.
Try it and see for yourself :thumbsup:


Then there's whole issue of why cannot algae use the same chemicals to fight each other and against plants?
Chara does it it might seem. 

I fully agree with the main point in the discussion, but with BBA and organics, why does it NOT grow in my non CO2 tanks? Consistently and without fail? 
those tanks get no water changes except once every few months, lots of organic build up.

Excel dosing, well, it's a selective biocide. Still, works best when using a non CO2 gas enrichment method to retard algae. 

You might suggest the rates of organic loading are more a factor, rather than just the concentration perhaps. Organic loading can come from many sources and has many types.

Ultimately, I think for hobbyists, they can run around and chase all this stuff, or stick to the basic and focus on plants, and good general aquarium care.

I'd not stick my neck out on the allelopathy issue though. there's just way too many cases that show it does not impact planted tanks. 

I think there's some link with bacteria in the sediment and the roots and shoots. Might be simply a nice established community partnership with plants, that does not happen with algae. 

Tanks never seem to do well till the roots grow in well, but..........if the root do not grow in well, you have a plant growth issue also, so..that's a toughie also.

But after the roots grow in and the plants bloom out some, then the tank is pretty tough.Frequent water changes in the 1-2 month phase dramatic helps establishment without algae for CO2 enrichment. This runs counter to the allelopathic hypothesis and what Walstad suggest for non CO2 soil based tanks with no water changes. How does the plant know if it's in a small puddle or a large lake? Say Lake Tahoe, or the Fall river, the CA Delta(FW tidal) or a small 1/4 acre pond? I've seen Eurasian Milfoil growing very well in all these places. That's a massive difference in habitat. Same for P crispus. Dang weeds.

Still, you need not a PhD to be a good farmer or aquascaper:thumbsup:
Elbow grease likely will serve you much better.


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## NeonFlux (Apr 10, 2008)

An excellent explanation about the main causes of algae outbreaks in planted tanks. Great read, nice write-up, and good conclusions. Now I better make sure I fertilize a little more frequently than ever, since I did increase my plant loads quite a bit as of late in some of my planted tanks. Grateful for the insightful information, Zapins.


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## Glenn Millar (May 25, 2014)

This is great info for me here with perfect timing....i have just started to see some sort of beard algea on some of my plants and tiny green dots on the glass so i did a water change yesterday ,i upped my co2 slightly an im still trying to find the sweet spot for that....i use profito fertilizer as directed once a week but here is where im unsure .

after i made the 30% water change should i start my weekly dose of profito on the day or just wait for the day i normally add....

iv just removed nutrients which could actually slow down my plant growth and might help the algae rather than put it under pressure

last week i reduced my lighting down to 6 hours too from 9hours...


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## Zorfox (Jun 24, 2012)

Very nice article Zapins. I like the fact that you're willing to question the current comprehension of the ecology of the planted tank. In particular, allelopathy.

The debate over allelopathy in the planted tank seems to be quite polarized in my opinion. It's either the "missing link" for algae control or it has no effect whatsoever. My belief is the answer lies somewhere in the middle.

Clearly allelopathy exists. However, allelopathy is a rather general term used to describe a large array of compounds and effects.

I had a tank with a thick carpet of dwarf hairgrass. I noticed a couple of stray crypts had taken root there. I essentially ignored this more out of laziness. After several weeks I quit ignoring it. The crypts in the hairgrass would not grow. They simply existed. On the other side of the tank the same plants grew like weeds. Allelopathy? It seems so. Eleocharis secrete allelopthic compounds at the roots. This isn't algae but it does suggest allelopathy plays a role in the planted tank.

I do question the idea that allelopathy plays no role on algae in the planted tank due to factors such as dilution, water changes or removal via AC. This argument assume that allelopathy can only occur in the water column. I do agree that the allelopathic compounds would have no effect in the water column as a result of these factors. However, there are concentration gradients that need to be considered.

Effluents affect ecology of rivers at a much higher rate around the discharge area. Where as miles down stream the ecology seems unaffected. If we scale that same effect down why couldn't the allelopathic compounds have an effect on algae at the site of discharge? It would seem an effective defense against algae attaching to plants blocking valuable resources. This mechanism would be unaffected by the size of the body of water and to a lesser degree the velocity of current. Conjecture? Absolutely! Yet it is a possibility.


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## Hoppy (Dec 24, 2005)

From a practical standpoint what would you do differently if allelopathy was occurring as a weapon plants use against algae, versus if it isn't occurring? And, what experiment, short of removing big organic molecules with AC, would you do to demonstrate the presence of allelopathy as a plant weapon vs. algae? If you would do nothing different, and if you can't find any experiment to demonstrate allelopathy, does it matter whether allelopathy exists as a plant weapon vs algae? If the answer is that it doesn't matter, then it becomes irrelevant.


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## Hoppy (Dec 24, 2005)

We often talk about soil tanks or nutritious substrate tanks as being those with low nutrient levels in the water. I'm not a chemist, nor am I a botanist, so I lack some basic information. Is it true that plants can use nutrients only if those nutrients are ions? Molecules which don't release ions into the water when they are in water would therefore not be available as food to the plants? But, ions in water are always equalizing concentrations throughout a body of water, "flowing" from high concentration areas to low concentration areas. So, is it possible to have a high available nutrient substrate and low available nutrient water in the same tank? Doesn't that make it obvious that available nutrients in the substrate must also be available in the water at near the same concentrations?


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## Zorfox (Jun 24, 2012)

I honestly don't think the average hobbyist can determine whether allelopathic algae control exists or to what degree. The current techniques do work. Is it because of this or that? That's the question.

Humanity seems to be one part survival and two parts curiosity IMO. Does it really matter what happens to matter when it enters a black hole? Yet we spend enormous amounts of money to research curiosities such as this. Sometimes, we can directly use the information we discover. Other times we can't. However, we can build on what we've learned to discover things that are useful in everyday use. I think it's simply human nature to ask why. We could continue to do XYZ and have positive results. Yet without full understanding we will never know if the positive results we seek are the maximum we can obtain.

I'm not a chemist or botanist either. However, I would think the nutrient concentration in the substrate would be higher than the water column. The ions in question have to be close to one another to react. Without adequate turn over those ionic concentrations would not equalize. It's much like a smokers lungs. The volume of air in the lungs are normal yet the gaseous content in the blood is blocked from various barriers. So basically, the two polarized ions would be less likely to meet in the substrate versus in the water column. At least that's my over simplified and ignorant view on the process.


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## Hoppy (Dec 24, 2005)

As I see it, when a substance dissolves in water that substance's molecules separate into ions, equal numbers of cations and anions. Those don't recombine in the water, but circulate in the water freely. In an underwater substrate, the same thing happens except that if the substrate has an appreciable cation exchange capacity, the cations are held in one place by the substrate, with the anions circulating in close proximity. But, a low CEC substrate can't grab and hold the cations, so they can freely move into the water that isn't in the substrate. Conversely, dissolved fertilizers in the water also consist of cations and anions, which freely migrate into the substrate water. That leads me to believe that a nutritious substrate, ADA Aquasoil, for example, causes the tank water to also be loaded with fertilizer.

I agree that even though we can't use our knowledge about allelopathy, for example, it is still interesting to gain that knowledge, and possibly apply it in a new way.


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## Zorfox (Jun 24, 2012)

Hoppy said:


> Is it true that plants can use nutrients only if those nutrients are ions?


That's my understanding as well. 

The amount of nutrient leaching would vary based on the substrate type. Rich organic substrates, such as organic soil, would have a much higher nutrient concentration than the water column. Sure there is some leaching yet the bulk of nutrients will remain in the substrate. Organic substrates have a high CEC which means cations, such as NH4, will be attracted and "bound" to the substrate.

Inert substrates could theoretically equalize if there was sufficient flow through the substrate. However, most people don't use UGF. If substrate fertilizers are used in an inert substrate the concentration would still be higher than the water column. Again there is some leaching that occurs but not enough to equalize nutrient levels.

Many people see an algae outbreak when uprooting a lot of plants or rescaping. Ammonia levels are greater in the substrate of an established aquarium. So disturbing the substrate releases ammonia leading to algae.

So to have high levels of nutrients in the water column from leaching, the substrate would need to be very rich. Much more so than the water column. That's basically how I see it. Right or wrong.


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## Hoppy (Dec 24, 2005)

Zorfox said:


> That's my understanding as well.
> 
> The amount of nutrient leaching would vary based on the substrate type. Rich organic substrates, such as organic soil, would have a much higher nutrient concentration than the water column. Sure there is some leaching yet the bulk of nutrients will remain in the substrate. Organic substrates have a high CEC which means cations, such as NH4, will be attracted and "bound" to the substrate.


I agree that high CEC substrates would hold nutrients, thus limit the leakage of nutrients into the water column.


> Inert substrates could theoretically equalize if there was sufficient flow through the substrate. However, most people don't use UGF. If substrate fertilizers are used in an inert substrate the concentration would still be higher than the water column. Again there is some leaching that occurs but not enough to equalize nutrient levels.


Ions in water will always migrate to areas of lesser concentration. This is an example of entropy, where everything tries to achieve zero differences in any attribute. No water circulation is needed, since ions are always moving around in the water.


> Many people see an algae outbreak when uprooting a lot of plants or rescaping. Ammonia levels are greater in the substrate of an established aquarium. So disturbing the substrate releases ammonia leading to algae.


Agreed, but I don't know what mechanism acts to release the ammonia.


> So to have high levels of nutrients in the water column from leaching, the substrate would need to be very rich. Much more so than the water column. That's basically how I see it. Right or wrong.


I don't think that is correct. Nature always works to make everything equalized. That is the basis of entropy.


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## Zapins (Jan 7, 2006)

I'm glad you are discussing this idea. I have enjoyed reading your comments. Unforutnately I have been extremely busy studying since I posted this. I'm doing gross anatomy in my first year of medical school so my time is limited. I will reply briefly now, but will try reply more fully soon.

Hoppy - yes, for nutrients to be absorbed they must be in ion form. This is because only ions are soluble in water (polarity of the ion allows it to dissolve in the weakly polar water). The dissolved nutrients are used by the plants.

However, there is definitely a pretty hard and fast barrier to nutrients in soil systems. The substrate cap blocks a lot of nutrients from reaching the water column. This is because although nutrients dissolve into the water in the soil layer this water does not exchange with water column water in huge amounts. The exchange of water between the two layers is therefore limited. This can be verified by test kits if you like on mature soil tanks, but also by the fact that ephiphytic plants like anubias/ferns often develop deficiencies when grown in soil tanks when they are not directly planted in the soil layer. 

On top of this, a lot of nutrients in the soil layer are produced over time by decomposition. They are locked up in organic molecules that are not as soluble as salts like KNO3, KH2PO4. Most of these highly soluble salts are flushed out of the soil layer within the first few weeks of setting a tank up, this is also why you must add potassium to aquasoil after a few weeks (potassium salts are very soluble). Then over the next several years most of the nutrients the plants have access to come from decomposition or from the CEC properties of the soil. So the water column of a mature soil tank is deficient of nutrients compared with an EI or PPS based tank. Remember, it only takes a total lack of 1 nutrient to stunt algae or plant growth and cause the organism to die eventually. Minerals like Ca/Mg are not deficient in the water column, but N and P and probably a few others are which is enough to make growing conditions unfavorable for algae or plants that have no access to the soil.


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## Hoppy (Dec 24, 2005)

Zapins said:


> I'm glad you are discussing this idea. I have enjoyed reading your comments. Unforutnately I have been extremely busy studying since I posted this. I'm doing gross anatomy in my first year of medical school so my time is limited. I will reply briefly now, but will try reply more fully soon.
> 
> Hoppy - yes, for nutrients to be absorbed they must be in ion form. This is because only ions are soluble in water (polarity of the ion allows it to dissolve in the weakly polar water). The dissolved nutrients are used by the plants.
> 
> ...


Interesting! Thank you. The Devil is in the details:redface:


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## RisingSun (Jan 5, 2014)

Your original post was a great read!



Zapins said:


> This is because although nutrients dissolve into the water in the soil layer this water does not exchange with water column water in huge amounts. The exchange of water between the two layers is therefore limited.


This is a very interesting phenomenon that I didn't know about, but totally makes sense. I think the ADA people, with their nutrient rich substrates and their meticulous removal of rotting plants, support ur point. High substrate nutrients, low water column nutrients.

I also strongly agree with your point on BBA and organics. I used to keep a turtle in a non-CO2 tank with some stones and plastic ornaments. I had no BBA problems in this tank. One day I decided to buy some anubias plants because I thought they looked nice in the tank. This was before I had any experience growing plants and my anubias slowly turned yellow and rotted away. Once that started happening, I started getting BBA growing all over my rocks. 

With my new CO2 tank, I noticed I got more BBA when I increased flow (added a koralia wavemaker) and when I didn't keep up with filter maintenance. Although these might well be correlations since there are many more factors in this new tank than in my previous tank.

I'm not sure about the allelopathy argument, I think Tom makes a strong case.

All in all, I hope you keep posting your observations!


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