Too much CO2?

[NewObsession]

So I set up DIY CO2. I have a setup similar to the 2Lpop bottle. I also bought a system similar to the Hagen (it was being cleared out and it was worth it just for the ladder). I hooked both up to the line into the tank. Am I running the risk of an algae outbreak if I O.D on the co2 without a lot of lighting? Its a 20XH tank with ~25 watts of 6500K lighting

[theotheragentm]

If the light isn't there, you shouldn't need CO2. The need for carbon in plants follows the need for light. Light would be your limiting factor depending on your photo period.

[NewObsession]

oh NOW you tell me lol.
Understandable, but if you put a number of plants in a tank, it will not "dilute" the light available for each, but would you not quickly deplete the amount of CO2 in the tank and require more?

[theotheragentm]

Light is generally measured was watts per gallon. This is based on T12(?) lighting. Different types of lighting actually give you different watts per gallon ratios. The only way plants steal light from other plants is if they're shading them.

Once carbon is used by plants, macro nutrients are necessary, followed by micro nutrients. It's a whole process that I haven't figured out completely, but as long as things are in balance, you will have plants out compete the algae. Just remember that it all follows lighting.

[Mgamer20o0]

its very hard to od on co2 in diy. its would only be harmful to your fish. maybe if you did 5-7 2 liters maybe you could do it with diy.

[jmhart]

As mentioned, it's likely that with that little lighting, your plants aren't using the added co2. It's most likely just being wasted. Without energy(from light) plants can't convert co2 into useful carbon.

You can keep running diy co2, it won't hurt anything(no fish death, no additional chance of an algae bloom), but it's probably not doing any good.

[Canuck]

I believe CO2 can help in a low light tank. I think Tom Barr at one time theorized that an abundance of CO2 and other nutrients allowed plants to untilize lower light levels at a greater efficiency. The theory went something like the easy availability of nutrients allowed the plant to utilize more energy in collecting the scant resource in this case light. That isn't to say that a low light tank with CO2 will outgrow a high light tank with CO2, but will do better then a similar low light tank without CO2. The basic premise of EI is nutrients in abundance.

[jmhart]

I believe CO2 can help in a low light tank. I think Tom Barr at one time theorized that an abundance of CO2 and other nutrients allowed plants to untilize lower light levels at a greater efficiency. The theory went something like the easy availability of nutrients allowed the plant to utilize more energy in collecting the scant resource in this case light. That isn't to say that a low light tank with CO2 will outgrow a high light tank with CO2, but will do better then a similar low light tank without CO2. The basic premise of EI is nutrients in abundance.


I suppose that this is only speculation. My extremely simplistic thought is that if plants were capable of using elevated(or rather, excess) co2 at lower light levels, plants would continue to grow even at night, where there is an excess of co2 over the available light. Rather, plants use this time to convert the available co2 into malic acid, which they then convert into usuable carbon when light is again available.

Now, you may say "But Jeffrey, some plants do grow at night" To that I reply "There is an exception to every rule".

[phanmc]

Even in a low light setup CO2 is usually the limiting factor, it just isn't as noticeable because the plants usually recommended for low light levels don't require are hardy with low CO2 requirements. Add CO2 and you'll see improved growth.

It is unlikely you'll be able to overdose CO2 with a DIY setup and an OD of CO2 won't cause algae, though it will kill your fishes. If you're afraid of a possible OD, get a drop checker.

[Canuck]

My extremely simplistic thought is that if plants were capable of using elevated(or rather, excess) co2 at lower light levels, plants would continue to grow even at night, where there is an excess of co2 over the available light.

But it isn't just the lack of light that stops plants from growing at night. Plants need to enter into a period of respiration. I think we have to draw the distinction between low light levels and levels of light so low as to be unuseable.

[NewObsession]

my thoughts were that 1 plant in a low light tank won't really benefit from CO2 if it doesn't have the excess light, however with a number of plants in a low light tank, is it not possiblethat betwen them they could use up whatever Co2 is naturally available? or would they use that little in low light that even in a heavily planted low light tank they would not use it all up?

[NewObsession]

in addition tothe question of OD'ing on CO2, I have posted this in the freshwater forum:
in my 20XH tank I am running DIY CO2 along with a couple low light plants and 6-7 water sprite. I was told the CO2 probably wasn't necessary but couldn't hurt and i tw as almost impossible to overdose on it unless my fish were gasping at the surface.
SO.... I was watching the tank last night and the furcata rainbows and Endlers all seem to be swimming right at the surface, almost like skimming for food I was worried that I had hit the point where they were running out of O2. However the platies and the neon and cardinal tetras are all swimming mid level and don't seem to be having any issues. Thoughts? Suggestions? picking up a drop checker to monitor the CO2 levels but any help would be appreciated.

I thought I would pose part 2 of the question in here since plant people tend to have a better understanding of CO2 than "non plant" people. We will be away for a coupleof days over the holidays, and while I am not concerned about the fish since I know a day or 2 without feeding isn't something to worry about, with the lights being out for a few days and not a lot of ambient lighting, would I be better to unhook the CO2? ( I have one little canister that came with a kit and a 3l Juice bottle with jello/yeast)

[livingword26]

I know my guppies would often stay at the surface at night, when the rest of my fish were at lower levels. Also CO2 will not remove O2 from the water, so even if your DIY CO2 generator was working at peak efficiency, it would not remove the O2 from the water. How big are your plants, and do you have any surface agitation? Any chance of a picture?

[NewObsession]

no pictures unfortunatly. No surface agitation since I minimized it so as not to lose CO2. Have 2 Vals ( sorry don't know the names) 6-7 water sprite and another low plant I picked up on the weekend, of the anubis(?) family I believe. listed as low liught and slow growing, mostly for ground cover. I know it doesn't displace CO2, and I reassured myself that the lack of surface agitation should be made up for by the plants producing O2 right? Just wasn't sure if I should unhook it for the couple of days the lights won't be on since I realize I am probably more overstocked than I should be (although the rainbows are all very young still and much smaller than they will eventually get.) My concern wasn't so much the CO2 displacing the O2 as it was worring that without the surface agitation that the water would get oxygenated enough to sustain the fish load

[phanmc]

Too much surface agitation will drive off CO2 but no surface agitation or movement will not allow gas exchange for 02 to enter the tank. In a heavily planted tank O2 may not be a problem but it's still possible. You're looking for a balance where you aren't wasting excessive amounts of CO2 while also maintaining a proper 02 level throughout the day and night. Increase the surface movement so you have a gentle ripple but not to the point where the water splashes.

[InTr4nceWeTrust]

If the light isn't there, you shouldn't need CO2. The need for carbon in plants follows the need for light. Light would be your limiting factor depending on your photo period.

CO2 can still help. This tank has 1wpg T8, 30ppm CO2 mist. NPK + trace daily:
http://img136.imageshack.us/img136/7231/cryptsen2.jpg

Original post can be found here (http://www.aquaticplantcentral.com/forumapc/general-aquarium-plants-discussions/46667-excellent-list-plants-low-light-tanks-3.html).