Sir Douglas Cook wrote:


Quoted from the book:
"C02 injection. In recent years some aquarists have used this process,
whereby carbon dioxide is added (from a gas cylinder) to the aquarium, in
order to promote plant growth. CO2 injection must be used with considerable
care, if at all. Remember that high CO2 levels may reduce the oxygen uptake
of the water and lead to a risk of hypoxia in the fish, especially if the
aquarium is crowded and /or the fish include species with a high oxygen
requirement. Some aquarists try to get round this problem by using
additional aeration, but, while this will certainly increase the oxygen
content and benefit the fish, it will at the same time drive off the carbon
dioxide, making the CO2 injection a rather pointless exercise! CO2 injection
should always be turned off at night - When the plants do not need it."

While I do not wish to enter into a debate with anyone
I think there is another important factor that has been missed
CO2 injection reduces ph
by turning on and off the injection system you may be causing ph swings
that could greatly harm your fish


Kris