# Which tank could get away with less light: non CO2 or a CO2 enriched tank?



## plantbrain (Dec 15, 2003)

And of course, why? Explain.

This question came up in discussion of the low light in the ADA hoods.
I posed it and many thought it was the non CO2 aquarium.

Regards, 
Tom Barr


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## Church (Sep 14, 2004)

Both. Because low-light tanks don't need CO2 enrichment, yet having CO2 enrichment does not negatively impact low-light tanks.

Did I win?


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## macclellan (Dec 22, 2006)

Without testing it, I'd say the same as Church - the same. This is assuming all else equal (stocking, feeding, fert regime, maintenance, etc). CO2 wouldn't be the limiting factor in either case - light would be. At best, I'd think the co2 enriched tank would do better. At worst, it would be a waste of co2.


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## Allen121 (Oct 22, 2008)

My assumption would be that the non-CO2 infused tank would get along with less light as opposed to the CO2 infused tank, due to the fact that the light is what permits the plants to make use of the CO2 in the first place from what I've read, so CO2 infusion into a low light tank (within reason) would be a waste at best, and cause an imballance leading to algae blooms and possible cyanobacteria at worste. It would not adversely affect the plants directly, but the results it might have on the water chemistry certainly seems like it could. This is all assumptionhowever based on a lot of reading recently, as I've been toying with the idea of increasing my light output and creating a DIY CO2 system for my own tank, so pardon my "newb ignorance" if I'm way off base, LOL!


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## original kuhli (Nov 28, 2006)

never mind...read the question wrong...


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## dogdoc (Feb 26, 2006)

I'm gonna go out on a limb and say the CO2 tank. 

My experience starting out was to go with a triple tube strip light on my 75. No CO2, ferts etc. The plants lived, but I wouldn't really say grew or thrived. I had to make a choice of what to upgrade first and chose a pressurized CO2 system. Without changing any other variables, the plant growth really increased, and all the plants looked better.


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## original kuhli (Nov 28, 2006)

Exact same experience here dogdoc, 160 watt over a 135 gallon tank, poor growth before CO2, great growth with CO2 and no ferts. You have to think that the CO2 affords the plants a better ability to compete with algae for nutrients.

After all...that's why this post is here isn't it! :icon_roll


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## plantbrain (Dec 15, 2003)

Hint time:

http://www.tropica.com/go.asp?article=792

Read this and each of the parts.

Then decide.


Regards, 
Tom Barr


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## JDowns (Mar 6, 2008)

I won't answer because of an unfair advantage in having discussed this quite awhile ago.

But I will fix your link. As I believe this is the article you are referring to.

http://www.tropica.com/article.asp?type=aquaristic&id=835

or I could be wrong and its the four part series eluded to in the above article

http://192.38.244.204/article.asp?type=aquaristic&id=142


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## JDowns (Mar 6, 2008)

I think people that have had problems with HC or other termed "high light" plants should read that thoroughly.


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## plantbrain (Dec 15, 2003)

Thanks for the link fix.

That's not my personal source, but describes the issue well enough for folks to get the answer. And it's one of those articles that's been around for sometime, but many many new folks have never bothered to read.

Regards, 
Tom Barr


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## original kuhli (Nov 28, 2006)

My summary:

CO2 is the principle limiting nutrient in aquatic systems. One can therefore assume that even in a lowlight tank CO2 and not light is the limiting nutrient for photosynthesis. 

Even low light tanks need CO2, and a CO2 enriched tank will provide for greater photosynthesis than will a non-CO2 enriched tank.

(note the use of the word assume)


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## Church (Sep 14, 2004)

Okay, so unless you worded your original question ambiguously, I still believe the answer is "*both* tanks can handle less light." I just finished reading that article, and I believe it confirms my stance.

Unless you were trying to say "which one of these tanks, a co2-enriched one and a non-enriched one, would be the most efficient at photosynthesis under low-light conditions."

But that's not how I read it. Nor, it seems, is that how macclellan read it.

What's my prize? :biggrin:


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## bsmith (Jan 8, 2007)

What would happen if you injected co2 to say 30 ppm in a low light tank >1wpg? Would it have the same side effect as over dosing nutrients?


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## plantbrain (Dec 15, 2003)

original kuhli said:


> My summary:
> 
> CO2 is the principle limiting nutrient in aquatic systems. One can therefore assume that even in a lowlight tank CO2 and not light is the limiting nutrient for photosynthesis.
> 
> ...


Your rational is correct.
Think about the law of the minimum that Liebig discusses.
Now think about which are the most limiting, light or CO2?

If you read the article and read it carefully, a plant requires less resources to be allocated to "catching CO2" in an enriched high CO2 tank vs the non CO2 tank. This means the plant has more resources to "catch light".

Both Chl a and Rubsico both are very nitrogen rich molecules, so if you need less for Rubsico, the CO2 catching enzyme, then you have more resources to allocate for Chl a.

Thus the CO2 enriched system will be able to grow at a lower light intensity and have a lower minimum thereshold of light, the light compensation point.

Generally, the advice on most forums is to not use CO2 under lower light situations, however, this is counter to what is observed and theorized if you think about things in the above terms.

Low light reduces the rates of growth, a great deal and can slow them way down(by a factor 10X or so) even if you are using CO2.

Light is the critical part here.
Many folks suggest adding more light for better growth, while true if the CO2 supply is still the same and increased appropriately as well, often folks don't do that.

The general point is that folks may consider adding CO2 before considering the addition of more light. I think folks will have more success overall and much less algae.

But so many folks think they must have higher light or they need it for so and so species of plant, or for better colors etc.

Leggy plants take some time to adapt to the current conditions and if you change them, they will reach for light, but after a ,month or so, they are fine and have adapted to lower light.

Enzyme and biochemical reorganization does not happen _instantenously_.
It can takes a few days, weeks etc. When folks see leggy growth, they think it means the plants will always do this under low light.

The rates of growth are also important, it's easier for a plant to assimilate nutrients from fish waste, various other sources such as the sediments and the water column, thus you have better growth appearance, but slower growth, a general consensus many desire.:thumbsup:

The folks that often buy CO2 generally bought too much light, and it's often rare folks buy CO2 first, and keep their low light.

So you get HLD........

And folks are generally an impatient lot.

There is a case, at leats in theory where one might have equal limitation power on both light and CO2 at the same time, but this is a theoretical knife's edge, very hard in practical terms to have.

One way or the other, the see saw tips. 
So in practical terms, not going to happen. I does happen in some cases where N and P bob back and forth in highly limited ocean systems. Co limitations can occur, but they generally go back and forth.

Adding more light will also reduce the demand for Chl a, as less is required, but this works much less so, algae, unlike plants, are not CO2 limited.....they are in general, light limited.

So you can have non CO2 tanks with higher light and easier to grow species that are aggressive and able to live pretty good under CO2 limited conditions.

Read the Tropica article a few times.

You will get it.

Regards, 
Tom Barr


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## Hoppy (Dec 24, 2005)

bsmith782 said:


> What would happen if you injected co2 to say 30 ppm in a low light tank >1wpg? Would it have the same side effect as over dosing nutrients?


Overdosing nutrients has little or no effect, if you do regular 50% water changes to control the maximum concentration of any nutrient in the water. Adding a lot of CO2 to that very low light tank would simply keep CO2 from being the limiting nutrient. Then the plants could grow as fast as the light permitted them to grow. CO2 is the main nutrient for all plants.


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## macclellan (Dec 22, 2006)

Thanks for linking to Tropica. Good read.

The question in the title of this thread is still ambiguous though and I don't think what I said above is wrong, even having read the article. According to Tropica, there was still growth when co2 and light where at limiting conditions, so both co2 enriched and non-c02 enriched tanks can "get away" with very low light levels...


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## plantbrain (Dec 15, 2003)

Yep, but you still can grow plants at lower levels with CO2 enrichment than you can with non CO2 methods.

If you get really low............to the LCP, then the relationship changes because there's such little light that the demand for CO2 is insanely low as well, so then it no longer matters.

But that;s a really low range where species to species issues will cause you issues and you will not be able to keep many species.

Another issue is that some species will compete much more for CO2 than others at low CO2 vs high CO2, so the plants will not do well, but that is due to CO2 and less to do with light. Some species may be much better at low light than others. So as you get lower, things fall apart and break down somewhat. But you can still drop things waaaaayyyy down without too much issue. 25-30micromol seems pretty good for many species.

Folks often suggest lighting that's 4-6x this amount.

The main point of all this is that lower light tanks do really well with CO2.
Many think low light => go non CO2.

This is unfortunate.

There is a lot to gain by using CO2 at low light.

Regards, 
Tom Barr


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## bsmith (Jan 8, 2007)

Maybe I should have been more specific.

Has anyone ever heard of someone running co2 on a low light tank and have an algea outbreak? I have not.

Has anyone ever heard of some one overdosing nutrients and getting an algea outbreak? Yes, but they didnt mention water change regimine.



Hoppy said:


> Overdosing nutrients has little or no effect, if you do regular 50% water changes to control the maximum concentration of any nutrient in the water. Adding a lot of CO2 to that very low light tank would simply keep CO2 from being the limiting nutrient. Then the plants could grow as fast as the light permitted them to grow. CO2 is the main nutrient for all plants.


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## plantbrain (Dec 15, 2003)

macclellan said:


> Thanks for linking to Tropica. Good read.
> 
> The question in the title of this thread is still ambiguous though and I don't think what I said above is wrong, even having read the article. According to Tropica, there was still growth when co2 and light where at limiting conditions, so both co2 enriched and non-c02 enriched tanks can "get away" with very low light levels...


Yes, both can when you get down low enough, but note, this was with one species, a mix might and will have different results and plant= plant competition.

Some species are better than others at lower light, some better at lower CO2.
If you remove CO2 as a limiting factor and leave just light, you will find more species are able to grow well at lower light.

Everyone is right in some context.

Whether you are or not is not really the point I am trying to make, rather, think about light/CO2 and low light.

How will effect my tank and is it a good idea?

There is a very strong bias towards both high light and towards CO2 enrichment together. Getting folks thinking about low light and CO2, or non CO2 methods as a good way to reduce and slow rates of growth, make their routines easier, less work etc, is the main goal here as well.

See if you can justify it via Liebig's min law, and see if co limitation might occur and when/where.

Regards, 
Tom Barr

Regards, 
Tom Barr


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## original kuhli (Nov 28, 2006)

I have had bba in a CO2 enriched tank with no ferts...thats what caused me to start adding ferts actually. Solved the problem...the bba was an indication of nutrient inbalance.


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## bsmith (Jan 8, 2007)

:thumbsup:Thats what I was looking for. 



original kuhli said:


> I have had bba in a CO2 enriched tank with no ferts...thats what caused me to start adding ferts actually. Solved the problem...the bba was an indication of nutrient inbalance.


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## plantbrain (Dec 15, 2003)

Was it adding the ferts or was it due to the plants simply not growing well, thus becoming like plastic plants and a good substrate for BBA?

BBA will grow on various parts and equipment but not grow on the plants if the plants are happy.

Anubias are more prone % wise to most epiphytic algae since they have such slow growth rates, whereas something like Myriophyllum almost never has such issues.

And if the conditions are good for either plant, neither will get BBA.

This is not really the topic here, this is a BBA question.
I've never had BBA in a non CO2 planted tank to date.

Regards, 
Tom Barr


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## SpeedEuphoria (Aug 5, 2008)

Those are great links :thumbsup:. It was good for me to reread them all again.

Well I'm glad I made the right choice, to get my pressurized CO2 setup on my 55G with ODNO shoplight. My plants were doing OK, but some were at a standstill or just growing that slow. After 6hrs or so I would get very slight pearling, I could count the bubbles watching the whole tank, it would be less than 1 bubble per second for the whole tank. I just setup my CO2, now I get much more pearling on the whole tank, its hard to count(like it should be). This is only 2 days of having CO2 and its at a low level 1bps on a 55G. 

Deff can see the improvement, I'm sure when the plants adjust and I turn the CO2 up I will notice it much more.


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## plantbrain (Dec 15, 2003)

Seems many have forgotten about the Tropica Articles which are some of the best around.

One of the main things that these articles showed was that CO2+ low light does wonders. I think many of us knew this, but often times it can be tough as we do not have the data, so measuring things like ADA tank's light etc helps, measuring tanks over time, seeing how low you can go with a certain species and measuring light in such tanks.

Few have ever bothered to do this.
I suspect a lot more will be doing this with the group buy on the PAR meters.
Every local plant club should invest the 149$ for one for the group to use I think.

You do not need everyone running around with one, nor will test light daily etc, perhaps a plant tip etc, but not the general tank light.........

Still, while many think low light= best to do non CO2, I think folks shoudl certainly reconsider CO2 and low light.

It is a very good easy to maintain option, much easier and less trouble than the HLD folks..........

There are situations where you could argue for both scenarios to do better, but the idea of doing it(low light) is the main "bait" here.



Regards, 
Tom Barr


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## greatfish123 (Oct 14, 2007)

is low light for 8hrs + CO2 comparable to highlight for 4hrs + CO2. i.e do they have the same advantages?


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## original kuhli (Nov 28, 2006)

The tank where I had BBA w/CO2 and no ferts was a 135 gallon with a 4 bulb tank often running energy saver bulbs (4*32W) but sometimes 40 watt bulbs. I was growing anubias, saggitaria and Vals. The Sag and Vals grew fast enough that I supplied a few pet stores with em, on occasion growth would slow and there would be an outbreak of bba. The plants were nowhere near being plastic plants, the Anubias were also growing fast enough that I had many to sell or give to friends.

The bba appeared to be phosphate deficiency based upon my experience. EI solved it.

Should also mention, the hardness is about 8 to 10 dKH.


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## tazcrash69 (Sep 27, 2005)

I have a similar situation to kuhli's where I was constantly battling BBA in my 125 (water is about the same hardness, and it all started when I got sloppy with my routine). I got fed up with repeatedly treating with H2O2 and I cut the lights in half, and stopped the CO2. The BBA stopped growing and after a few more H202 treatments, did NOT come back for the first time. I turned the CO2 back on, and there were the little black tufts forming again on my driftwood and spray bars.  Turn it off, and they stop.

Now I'm hoping to wipe out the last of the BBA, and thanks to this thread start back on my CO2 dosing. 

great read from Tropica.


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## jerrytheplater (Apr 11, 2007)

plantbrain said:


> Thanks for the link fix.
> 
> That's not my personal source, but describes the issue well enough for folks to get the answer. And it's one of those articles that's been around for sometime, but many many new folks have never bothered to read.
> 
> ...


Tazcrash69 alerted me to this thread. I am new to posting on this forum, but I have been interested in BBA for a while. I read both articles, and it turns out I did read both in TAG but didn't recall them. It was a good refresher.

Question for Tom: you said these articles weren't your personal source. Were you thinking of other articles? If so, would you please post the link to them? Thanks.

Jerry Smith
Bloomingdale, NJ


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## tom855 (Jan 31, 2006)

Too bad none of these Tropica links seem to work any more. 
Sounds like a series of great articles!


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## Jeff5614 (Dec 29, 2005)

tom855 said:


> Too bad none of these Tropica links seem to work any more. A
> 
> Sounds like a series of great articles!


Tom, I think you'll find the articles here.

http://www.tropica.com/advising/technical-articles/biology-of-aquatic-plants.aspx


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## tom855 (Jan 31, 2006)

Thanks Jeff!

Not exactly light reading, but I'll definitely take time to read through them.

Thanks!

Tom


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## Jim Miller (Dec 24, 2002)

Since light is the energy that plants use and they must spend their energy wisely or die I would guess that anything that lets plants spend their energy on growth would be preferred. 

Since plants need carbon (carbohydrates...geddit?) and if its unavailable in the water column they will need to spend energy to get it elsewhere. That energy limits what they can spend elsewhere.

Just guessing...

Jim


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## burr740 (Feb 19, 2014)

Enlightening thread. Bump.


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## jeffkrol (Jun 5, 2013)

burr740 said:


> Enlightening thread. Bump.



My personal favorite part:


> Another issue is that some species will compete much more for CO2 than others at low CO2 vs high CO2, so the plants will not do well, but that is due to CO2 and less to do with light. Some species may be much better at low light than others. So as you get lower, things fall apart and break down somewhat. But you can still drop things waaaaayyyy down without too much issue. 25-30micromol seems pretty good for many species.
> 
> Folks often suggest lighting that's 4-6x this amount.
> The main point of all this is that lower light tanks do really well with CO2.
> ...


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