Kh/ph/co2

The relationship of ppm of CO2 to KH and pH for water that contains no other source of alkalinity but carbonates and no other source of acidity but CO2 is a mathematical equation of the form:
CO2 is proportional to KH divided by 10 to the power of the pH.

The problem is that aquarium water almost always has other sources of alkalinity and acidity other than carbonates and carbon dioxide, so the relationship isn't correct in most aquariums. That is why so many of us have "measured" our CO2 at 100+ ppm using that relationship, but the fish are not showing any effect. We do know that long before the CO2 concentration gets that high, all of the fish will die.

The answer to this problem is a drop checker. See the relevant threads on this forum.

 

Newbie here...What is the problem of High KH?

I ve been using a test kit that doesnt even show the starting color when I test my KH. Ive been dropping the solution one at a time by neither the starting color nor the end matches form the color. I live in Los Angeles area.

thanks!

 

High KH is a problem for some plants, but not many. And, a few fish prefer lower KH. So, since low KH doesn't appear to cause anything bad to happen many of us prefer to use low KH.

It sounds like your KH test kit is defective. My Aquarium Pharmaceuticals test kit gives a pretty easy to see color at both the starting color and the end color. My API GH kit, on the other hand, doesn't always work at all.