# Does CO2 Make a difference?



## K Randall (Nov 23, 2004)

While trying to hunt through photos of my old tank, I found these that I thought might be of interest. This tank (also set up for years, though newer then the one I just took apart) was first set up as a beta test tank for Seachem's product line. So that should give you an idea on age if you want to look it up. (it was too much work for me )

The tank is a 75G tank, and at that time had 2 32W T8 bulbs over it... pretty low light. Seachem had asked me to try their (then) new product, Excel on the tank, and NOT use supplemental CO2. The first photo shows the results using all Seachem products. Not bad. Not spectacular, but not bad.

At the end of the trial period, I happened to win a couple of those Hagen yeast CO2 reactors. They are small, and I didn't think I'd see much of a difference on a 75G tank with them, but I didn't have a smaller tank to try them on at the time. So I set them up on this tank. The second picture was taken about a month later, with NO CHANGES other than the infusion of that small amount of CO2. To me, THAT is a spectacular change, and shows how beneficial CO2 can be, even on a low light system.

Still can't seem to upload photos, so these can be found at: http://krandall.zenfolio.com/co2

BTW, anyone know when we'll be able to put photos up directly again?


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## Michael (Jul 20, 2010)

Not to argue that supplemental CO2 makes no difference, but I regularly see that much growth over a month in my established Walstad tanks.

I wrote that sentence before I read your recent excellent post in Niko's thread: http://www.aquaticplantcentral.com/...quatic-plant-club/85985-30-year-old-tank.html So I should add that my "Walstad" tanks" probably generate more of their own CO2 because of my higher animal stocking, higher imputs of fish food, and higher biofiltration rates. The biofilter may play a bigger role than I realize--all those little microorganisms are respiring constantly, and that CO2 must go somewhere. I try to minimize all surface agitation from my filter returns, so more of that respiratory CO2 may end up in my tanks than is typical.


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## aquabillpers (Apr 13, 2006)

I've seen the same thing that Michael has seen. After 6 weeks of inattention, I now have to do a radical pruning on a 10 gallon Walstad tank.

Of course, some plants need high lighting, and CO2 augmentation is usually required in that case. But most plants will grow just fine without it.

Bill


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## K Randall (Nov 23, 2004)

Michael said:


> Not to argue that supplemental CO2 makes no difference, but I regularly see that much growth over a month in my established Walstad tanks.
> 
> I wrote that sentence before I read your recent excellent post in Niko's thread: http://www.aquaticplantcentral.com/...quatic-plant-club/85985-30-year-old-tank.html So I should add that my "Walstad" tanks" probably generate more of their own CO2 because of my higher animal stocking, higher imputs of fish food, and higher biofiltration rates. The biofilter may play a bigger role than I realize--all those little microorganisms are respiring constantly, and that CO2 must go somewhere. I try to minimize all surface agitation from my filter returns, so more of that respiratory CO2 may end up in my tanks than is typical.


I'm sure you have more CO2 generated in your tank than this one had... This was set up with Flourite, was a relatively young tank, (therefore no real build-up of mulm) and I never stock or feed heavily. The point is that plants HAVE to have CO2 from somewhere to grow. If you can produce it within the system without causing algae problems, fine. If not, supplemental CO2 becomes necessary for good growth. It's not magic... if the plants are growing well, they are getting their carbon needs met, one way or another.

Oh, and many tanks can produce this amount of growth if cut back hard and allowed to re-grow. But in this case, the tank had looked like this... with very low growth, for many months, then suddenly blossomed with an infusion of just a small amount of CO2.


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## K Randall (Nov 23, 2004)

aquabillpers said:


> I've seen the same thing that Michael has seen. After 6 weeks of inattention, I now have to do a radical pruning on a 10 gallon Walstad tank.
> 
> Of course, some plants need high lighting, and CO2 augmentation is usually required in that case. But most plants will grow just fine without it.
> 
> Bill


I would argue that SOME plants will grow fine without supplemental CO2 and strong(ish) light, but many more can only be kept successfully in high light/CO2 enriched systems. There are, obviously, plenty of species to choose from in each category, so there are plenty to use no matter which way you go.


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## K Randall (Nov 23, 2004)

Oh, the other point I was trying to make with these photos is not that you can't grow plants without supplemental CO2, but that if things aren't going as well as you want, adding supplemental CO2 will improve your plant growth MUCH more than adding light, which is what many novices try first. (this is not up for debate, the studies have been done to prove it)


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## totziens (Jun 28, 2008)

I believe it depend on what type of plants. Some will continue growing like mad despite of no additional CO2 being supplied. I noticed I could grow moss better with CO2. Without CO2, it does not mean they will die but they don't look that pleasant. I am not referring to Java moss though. I refer to Spiky moss, Taiwan moss, weeping moss and Christmas moss. I also notice that the growth rate of plants being supplied with CO2 is faster for some stem plants (it could be quite annoying as you have to trim every week). I still keep tanks with and without CO2 due to personal interest. So, I am neither pro-CO2 nor anti-CO2.


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## K Randall (Nov 23, 2004)

totziens said:


> I believe it depend on what type of plants. Some will continue growing like mad despite of no additional CO2 being supplied. I noticed I could grow moss better with CO2. Without CO2, it does not mean they will die but they don't look that pleasant. I am not referring to Java moss though. I refer to Spiky moss, Taiwan moss, weeping moss and Christmas moss. I also notice that the growth rate of plants being supplied with CO2 is faster for some stem plants (it could be quite annoying as you have to trim every week). I still keep tanks with and without CO2 due to personal interest. So, I am neither pro-CO2 nor anti-CO2.


Many of those plants are not fully aquatic plants. They are plants that can withstand periodic innudation, but do most of their growing in the emersed state. So when we keep them sumbersed, they do much better with supplemental CO2. It is the widespread use of supplemental CO2 that has allowed us to maintain many of these species in the aquarium at all.


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## totziens (Jun 28, 2008)

In the wild, I believe many of our aquatic plants grow out of the water. I have tried throwing some Ludwigia repens, water wisteria and some unknown stem plants in an outdoor tank to let them grow wild. Most of them tend to grow out of the water if they're left alone. I supposed their attempt to reach out to the sunlight is another factor. Short plants like Helanthium tenellum, Marsilea, glosso, etc of course cannot do what tall stem plants could do to grow out of the water unless you have very shallow tank (maybe with 1-2 inches of water) 

Sorry, I think I am going out of the topic now...


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## wet (Nov 24, 2008)

I think it's worth adding that an experiment like this one -- adding nominal amounts of CO2 to a tank with many established plants -- is relatively safe. Doing this with DIY and check valve would be cheap. It's easy to revert. This is the type of experiment I think anyone running no CO2 should try. 

I also love this:

"if the plants are growing well, they are getting their carbon needs met, one way or another."

I'm interested in folks's experience going from CO2 (for the purposes of this post: CO2 gas added to the aquarium) to no CO2. Did the method stick? How'd you like those tanks?


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## AaronT (Apr 26, 2004)

This is exactly why I always recommend adding CO2 before adding more light. Even just DIY CO2 makes a HUGE difference in growth rates. From there you can determine if more light is necessary for the type of tank you wish to achieve. Most people would be surprised to see they don't need as much light as they thought to grow things like Glosso, hairgrass, etc...


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## totziens (Jun 28, 2008)

I've done CO2 to no CO2 with several plants as follows:

1. Ludwigia repens - in non-CO2 tank, it grows better when I leave them floating because the bottom part tend to rot away. However, insufficient lighting may trigger the rotting too.

2. Cryptocoryne wendtii - I cannot spot any difference. Maybe propagation is faster with CO2. Less algae occupying the leaves.

3. Helanthium tenellum - it grows faster with CO2.

4. Taiwan moss, Spiky moss, Christmas moss and weeping moss - they grow nicer and faster with CO2.

5. Potamogeton gayi - I could not keep them very well without CO2.


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## Bert H (Mar 2, 2004)

AaronT said:


> This is exactly why I always recommend adding CO2 before adding more light. Even just DIY CO2 makes a HUGE difference in growth rates. From there you can determine if more light is necessary for the type of tank you wish to achieve. Most people would be surprised to see they don't need as much light as they thought to grow things like Glosso, hairgrass, etc...


Well said, Aaron.

CO2 is definitely the one thing you shouldn't skimp on, IMO.


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## K Randall (Nov 23, 2004)

totziens said:


> In the wild, I believe many of our aquatic plants grow out of the water. I have tried throwing some Ludwigia repens, water wisteria and some unknown stem plants in an outdoor tank to let them grow wild. Most of them tend to grow out of the water if they're left alone. I supposed their attempt to reach out to the sunlight is another factor. Short plants like Helanthium tenellum, Marsilea, glosso, etc of course cannot do what tall stem plants could do to grow out of the water unless you have very shallow tank (maybe with 1-2 inches of water)
> 
> Sorry, I think I am going out of the topic now...


That is exactly my point. There are also many plants that we use in aquariums that are only occasionally under water, or only for short periods. (some of those tiny foreground plants you mentioned, and many of the mosses we use) These tend to do best with supplemental CO2


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## K Randall (Nov 23, 2004)

wet said:


> I think it's worth adding that an experiment like this one -- adding nominal amounts of CO2 to a tank with many established plants -- is relatively safe. Doing this with DIY and check valve would be cheap. It's easy to revert. This is the type of experiment I think anyone running no CO2 should try.
> 
> I also love this:
> 
> ...


When doing this sort of experiment (in either direction) it's really important to take periodic photos. Our eyes (and brains!) are deceptive. I didn't realize the change of growth in this tank until I had the photos sitting in front of me. Someone could remove supplemental CO2 from a tank, and think that everything is hunky dory. But then comparison photos could show weak, less healthy growth and a bit more algae.


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## K Randall (Nov 23, 2004)

totziens said:


> I've done CO2 to no CO2 with several plants as follows:
> 
> 1. Ludwigia repens - in non-CO2 tank, it grows better when I leave them floating because the bottom part tend to rot away. However, insufficient lighting may trigger the rotting too.
> 
> ...


Not at all a surprising outcome. Any plant that can reach the surface, then has access to atmospheric CO2 and can do fine.

Crypts, Anubias and Java ferns are all slow enough growers that unless they are seriously out-competed by other plants (there was a person with this problem at the convention) they can meet their carbon needs within a non-supplemented, low light "fish tank". That's why they are old "mainstays' in the hobby and have been popular for close to 100 years. Vals also do great in moderately hard water, but for a different reason... they can meet their carbon (not CO2) needs by accessing the carbonates/bi-carbonates in the water column. They don't need free CO2.

Helathium tennellum (and the other chain swords) are really marsh/marginal plants that grows close to the high water line on the rivers where it is found. It would only be submersed in certain season, and not for too long. So again, mostly it's carbon needs are met through the atmosphere. (though I have to say, this is a plant I did very well with, even in my pre-CO2 days, as did many "old timers")

The mosses you list are ones that are not REALLY aquatic... they grow in damp areas and spray zones around waterfalls. So you can talk them into doing well submersed, but only by providing ALL their needs, including CO2

We don't know a lot about Potomogeton gayi in the wild... Christel was only able to find it in one spot. But most pondweeds are usually full sun, high growth rate plants, and with that, comes a need for access to carbon. The easiest way to meet that need consistently in an enclosed glass box is with supplemental CO2.

So, I guess what I'm saying is that your observations are exactly what should be expected, knowing what we know about these plants in the wild.


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## aquabillpers (Apr 13, 2006)

It's a fact that additional carbon in the form of CO2 or in other forms, will make almost all aquatic plants grow faster. 

But, I'd say that most aquatic plants will grow well if more slowly without such augmentation.

Light is the most important driver of plant growth. Carbon is second. Most of the problems of aquatic plants posted here or at other sites are due to insufficient or excessive light, and are correctable by adjusting the light.

Bill


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## Michael (Jul 20, 2010)

Thanks everyone for a very interesting discussion. If I ever decide to change the way I manage my tanks, CO2 supplementation will be the first thing I try.

Some observations on plants mentioned in the discussion: Java and Taiwan moss and _Helanthium tenellum_ grow so fast in my Walstad tanks that they become troublesome. All the ludwigia species I have tried also do very well, and I do not let them develop emersed growth because of the shading problems that creates.


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## K Randall (Nov 23, 2004)

aquabillpers said:


> It's a fact that additional carbon in the form of CO2 or in other forms, will make almost all aquatic plants grow faster.
> 
> But, I'd say that most aquatic plants will grow well if more slowly without such augmentation.
> 
> ...


Actually, adding light in the absence of an adequate carbon source produces less growth (and more algae problems) than low light and adequate carbon source. There is research that proves this done by dr. Ole Pedersen at the University of Copenhagen.


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## aquabillpers (Apr 13, 2006)

K Randall said:


> Actually, adding light in the absence of an adequate carbon source produces less growth (and more algae problems) than low light and adequate carbon source. There is research that proves this done by dr. Ole Pedersen at the University of Copenhagen.


Karen,

I was talking about the common case where an aquarium does not receive sufficient light.

It is well known that excessive light without enough carbon (and other nutrients) will cause algae.

Bill


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## K Randall (Nov 23, 2004)

aquabillpers said:


> Karen,
> 
> I was talking about the common case where an aquarium does not receive sufficient light.
> 
> ...


Even tanks with very modest amounts of light will benefit from additional CO2 and it won't cause the algae problems that adding more light WITHOUT adding CO2 will.


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## totziens (Jun 28, 2008)

K Randall, thanks for the detailed information. It makes this topic very interesting.

I do agree that Vallisneria (Corkscrew Vallisneria in my case) is growing very well without CO2 supplied. I just let them grow in a tank at the balcony exposed to sunlight for very short duration. They somehow cannot grow well in my indoor tank supplied with CO2 and artificial light....there are also Crypts in my indoor tank (I heard Crypts and Vallisneria do not get along via this forum but it's a separate topic). I also cannot keep easy plants like Elodea and Hornwort very well indoor. These 3 plants I just have to leave them to grow wild naturally without human intervention except for water changes and occasionally put some of them into the bin. The more I care for them, the more trouble I give the plants.


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## K Randall (Nov 23, 2004)

totziens said:


> K Randall, thanks for the detailed information. It makes this topic very interesting.
> 
> I do agree that Vallisneria (Corkscrew Vallisneria in my case) is growing very well without CO2 supplied. I just let them grow in a tank at the balcony exposed to sunlight for very short duration. They somehow cannot grow well in my indoor tank supplied with CO2 and artificial light....there are also Crypts in my indoor tank (I heard Crypts and Vallisneria do not get along via this forum but it's a separate topic). I also cannot keep easy plants like Elodea and Hornwort very well indoor. These 3 plants I just have to leave them to grow wild naturally without human intervention except for water changes and occasionally put some of them into the bin. The more I care for them, the more trouble I give the plants.


Ha! It's funny that people will sometimes have trouble with some easy plant, while doing well with more difficult plants. It happens to everyone!


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## aquabillpers (Apr 13, 2006)

totziens said:


> K Randall, thanks for the detailed information. It makes this topic very interesting.
> 
> I do agree that Vallisneria (Corkscrew Vallisneria in my case) is growing very well without CO2 supplied. I just let them grow in a tank at the balcony exposed to sunlight for very short duration. They somehow cannot grow well in my indoor tank supplied with CO2 and artificial light....there are also Crypts in my indoor tank (I heard Crypts and Vallisneria do not get along via this forum but it's a separate topic). I also cannot keep easy plants like Elodea and Hornwort very well indoor. These 3 plants I just have to leave them to grow wild naturally without human intervention except for water changes and occasionally put some of them into the bin. The more I care for them, the more trouble I give the plants.


Vals and crypts (C. wendtii) grow profusely in my non-CO2 2 wpg (T12) soil based tank. They needing pruning every 4 to 6 weeks. I wonder if your indoor aquarium is getting enough light?

Bill


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## Tikulila (Feb 18, 2011)

Well, to add to this, I have returned my DIY yeast to my tank about 1 month ago, it's low light (planning on making it to a high light soon) and up to now after one month the was a small change for the worst (some algea). I think everything depends on keeping the perfect balance, of light, CO2 ect. 

I'll continue adding CO2 and will follow what will happen and update if you guys would like me to. 
Could be a nice test for CO2.


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## totziens (Jun 28, 2008)

I am pretty sure that my tank has sufficient light. Now the tank looks like a jungle with various plants except Vallisneria. Without Crypt, I could easily kept Vallisneria till I was tired of removing them (I often gave them away in the past before the crypts came along). Anyway, I am tired of Vallisneria these days - I am beginning to hate plants that need constant trimming and removal.


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