Does co2 help fight algae?

dereks

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Mar 7, 2006
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Does co2 help fight algae, or does algae like co2 just as much as other plants like it?

I can see how it would appear to help fight it, if it helps plants out-compete algae. Does that make sense?
 
Actually it does make sense. Co2 reduces excess O2 available to algae which is why you have to watch how much you are letting into the water, so you don't suffocate your fish. As long as there is sufficient for the fish and plant uptake, leaves little excess for the algae. The same applies to ferts that the plants uptake. Ferts and CO2 are great for planted tank management. You do need to monitor the levels available for lifeforms.
 
I've always been under the impression that adding CO2 (at the levels we see in aquariums) will NOT displace O2...at least not significantly. I would assume then that the reason fish get stressed under high CO2 concentrations is because they are no longer able to exchange O2/CO2 at the gills, but not because O2 concentrations have decreased dramatically. Also consider that properly growing (and photosynthesizing) plants will be producing O2.

This is just what I have heard though.
 
No Problems. I could very well have understood it wrong too. I don't use it in my tanks and has been a while since I last researched using it. I don't use it simply by choice as I need to keep things as simple as possible.
 
I've always been under the impression that adding CO2 (at the levels we see in aquariums) will NOT displace O2...at least not significantly. I would assume then that the reason fish get stressed under high CO2 concentrations is because they are no longer able to exchange O2/CO2 at the gills, but not because O2 concentrations have decreased dramatically. Also consider that properly growing (and photosynthesizing) plants will be producing O2.

This is just what I have heard though.

This is what I have read, had some trouble with my co2 levels a few months back and my gourami's had to hang near the surface constantly, im glad I invested in the drop checker. I think a lot of o2 displacement has to do with water surface agitation in the aquarium, and a constant co2 supply? They seem to have a lot more trouble breathing and hung near the surface to breath once I added my power head. After I got my drop checker I decided to invest in a better power head that had the o2 hose option. Not sure if this was the problem caused by my first power head and surface agitation, or if I should have just lowered my co2 levels, but I didn't think 2 bps was to much for a 29 gallon.
 
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You may need to add more plants to create more oxygen. Sounds like you may have a little too much co2 flow for the amount of plant life. Also it helps to gradually adjust co2 levels because it takes time for plants to adjust. Changing the co2 too quickly can effect the ph alot as well as give algae an opportunity to bloom.


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The amounts of dissolved CO2 and O2 are independent of each other, meaning one or both could be high or low. CO2 does not displace oxygen. Fish run into problems when CO2 is high relative to the levels of O2 available. Not commenting on this particular situation but gouramis are a labyrinth fish meaning they breathe air, typical behaviour would be for them to be top dwelling fish and gulp air. Since they do possess the labyrinth organ, I would expect them to be the last fish in an aquarium to be stressed due to low O2 levels.

CO2's effect on algae is more due to the strong healthy growth it promotes in plants, then any direct effect. I don't know why this works but it does. Even with plenty of excess nutrients (like those available when one uses EI), algae will diminish in the presence of lots of healthy plants. Starve your plants, limit available nutrients and your tank will soon be overrun with algae.

And not to be argumentative but most fish, and plants would be better off, if everybody lost their pH test kits and never replaced them.
 
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The amounts of dissolved CO2 and O2 are independent of each other, meaning one or both could be high or low. CO2 does not displace oxygen. Fish run into problems when CO2 is high relative to the levels of O2 available. Not commenting on this particular situation but gouramis are a labyrinth fish meaning they breathe air, typical behaviour would be for them to be top dwelling fish and gulp air. Since they do possess the labyrinth organ, I would expect them to be the last fish in an aquarium to be stressed due to low O2 levels.

CO2's effect on algae is more due to the strong healthy growth it promotes in plants, then any direct effect. I don't know why this works but it does. Even with plenty of excess nutrients (like those available when one uses EI), algae will diminish in the presence of lots of healthy plants. Starve your plants, limit available nutrients and your tank will soon be overrun with algae.

And not to be argumentative but most fish, and plants would be better off, if everybody lost their pH test kits and never replaced them.

This is why I decided to go with dwarf gouramis my first go around with a fully planted tank and co2 injection. I found a good article on fish gill morphology and the effects changing environments have on them if anyone was interested-http://www.jstor.org/discover/10.23...60&uid=2&uid=4&uid=3739256&sid=21101131431777 this article isn't free and I got it for research in my biology class, but I found it one of the most interesting articles I have read. Another good article about algae and the aquarium, I used this initially for my information on algae prevention and control, http://www.practicalfishkeeping.co.uk/content.php?sid=2999.
 
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