Hi all

Sorry to start with a question, I've introduced CO2 to my aquarium to help with plant growth and would appreciate some advice from a more experienced keeper.

I'm using a regulator, bubble counter etc. and checking that the CO2 levels don't go too high with 2 drop checkers.

I've only run it for about three hours per day as a start. Using an aquarium calculator my dissolved CO2 should be 20ppm and the drop checker closest to the diffuser turns lime green and the one at the other end of the tank a slightly darker green so I think I'm ok. Using PH and KH test kits, I now have PH of 7.2 and KH of 10 degrees (by best estimate) which confirms the above.

My PH 3/4 days ago was 8.0 - I was of course expecting the drop but do not really want to drop much further. My question is, how do I maintain these levels without dropping PH further, will maintaining a consistent level of CO2 keep my PH at this level or will it continue to drop? Or will I need to decrease the CO2 levels to maintain the PH levels (does that question even make sense).

While I'm comfortable with monitoring CO2 levels so that they are beneficial for both plants and fish, I'm really uncomfortable with causing fluctuations in my PH levels so would be really grateful for any help

You'll find that when the CO2 is off, the pH reverts to normal. Ph fluctuations due to CO2 injection are normal, and because they are caused by CO2 rather than by a change in the underlying water chemistry they have little effect on the fish so there's no need to worry about it unless you're getting huge swings above 1 on the pH scale.

Perfect, that's really reassuring.. Thanks for the reply Fishlady