Planted Tank Guru
Join Date: Jun 2012
Location: Gainesville, FL
The CO2 concentration needed to obtain maximal growth is different for every aquarium. The amount of CO2 delivered per second (bps) to obtain adequate levels changes from tank to tank. There are many factors that alter CO2 concentrations not to mention the overall need for CO2 by plants in a given tank.
Rather than watching a PH meter or drop checker watch your fish. Increase CO2 output in small amounts every couple of days until you see signs of stress. Then return to the output setting before stress was noticed. That will be the critical point where more CO2 is detrimental. Now you can look at a PH meter or drop checker to use as a GENERAL guide. Neither are perfectly accurate.
Things can happen quickly running a tank with a CO2 concentration that close to critical. Many prefer to reduce CO2 even more until plants suffer or algae appears then increase it just above that point. This balancing act is not a set it and forget it thing. CO2 will always require tweaking.