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Adding Co2

646 Views 2 Replies 2 Participants Last post by  gusto
Hi Everyone,
I just purchased a GLA regulator and I'm in the process of adding Co2, I also purchased a Glass drop checker.. My question is what's the best way to start adding Co2 without overdoing it.. I have a 29 gallon planted tank. I don't use an airstone and at one point I lost a fish and it looked like there might not be enough oxygen in the tank so instead of using an airstone I pointed the return (spray bar that goes the length of the tank) to the surface to have better surface aeration and that seemed to help with the oxygen but now my PH is around 8 and I wanted to lower it. I know adding Co2 will lower PH but what's the best way to try to equal out enough Co2 for the plants and enough oxygen for the fish. Thanks, Gus
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Maximizing O2 is always good and you are doing it in the right way (surface rippling is better than air stones). Inexpensive ($20-$30) skimmers are also excellent for gas exchange. Keep in mind that O2 and CO2 do not interfere with each other, i.e.; one does not displace the other.

Most of us target a pH drop from fully degassed water to fully gassed water ranging from 1 full pH point to a ~1.4 point drop. This can be done by letting a glass of tank water sit out for a day or two (can be accelerated by aeration), then measure the pH and compare it to your tank about two-hours, or more, after the CO2 is turned on. A one-point drop gives you about 30ppm CO2 and is a good starting target. Make sure that your KH readings remain identical in both the tank water and the sample water.

However, do this slowly, a little every day, until you reach your goal. Turn the CO2 up until your fish show signs of distress (usually gasping for air at the surface or lethargic near the bottom), then back it down a little (until they are happy) and wait a day to increase it further. It can take a number of days, up to a week, until fish adapt.

In your case, it seems that your fully-degassed water is pH 8.0. So, you would slowly move toward a target of 7.0 or less (6.5-6.6 is probably going to be the limit of what your fish can handle).
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