it can be too much CO2 or the CO2 has dropped the PH and the fish are dieing from acid water. If you add CO2 you should increase the carbonate hardness (KH) to prevent the PH from dropping.
Incorrect unless water parameters are so low already.
Noone I know ever does anything to maintain the original Ph. Most of us know and accept the Ph will drop by circa 1 Ph. Fact and we live with it as do fish. The same tropical fish are found in several different parameter even as low as 3-4ph. Many fish like Cardinals are found in parameters as low as 4ph.
As per previous comments. 30ppm is the recommended highest but not the highest you can go. Many people go to the 35/40level just to ensure they are past 30ppm. Not necessary as consistency is the main key but not deadly either. Is dangerously close though. Mine is nearer to 25ppm on pressurised.
I also agree with the people above in that A - It is nigh on impossible to overdose from DIY CO2. Not impossible but 2 x DIY kits on a 125 shouldnt be able to do it. B - I agree thats a lot of ingredients. Those bottles should be frothing and overflowing.
Going by the latter are you sure the ingredients arent creeping up the line and into the tank water?
My suggestion for a 2 litre bottle would be : 1 tea cup of yeast, 1 teaspoon of yeast, water up to where the neck bends. Change alternatively weekly. i.e. Weds 1 bottle and Sat the other.
Even with a top notch diffusor 2 bottles will struggle for 30ppm IMO.
CO2 does not mean less oxygen. There is an equilibrium. CO2 is harmful to animal life in the same way it is to us. If there is too much CO2 then when we breathe in Oxygen then we also breathe in CO2. If the fiush are at the surface they will be trying to breathe from the air above the water where this i not CO2 (or it is not as concentrated as in the water) There will still be as much O in the water just that to breathe it they are also having to breathe the CO2 with it at a high level.
AC
