How to lower CO2 in tank

[Giniel]

How do you lower the co2 level in fish tanks? I have a ph 6.8 , gh 3 drops , kh is about 5 drops , 0 amonia and 0 nitrites. I have tried to test my tank 3 times and it is well above 30 drops . Is this too high? I have a bare bottom tank with sponge filter and a hang on back of tank filter.I have a large air stick also.
Any replies are welcome..

[Anonapersona]

I see your CO2 would appear to be 23ppm, great for a planted tank but surprising for a bare tank.

The KH number might be invalid, take a sample of water and let it sit out overnight, even shake it well to drive off CO2.

If the pH does not change, then it is not CO2 giving those values, it might be an incorrect KH. High phosphates, like from foods, can alter the KH value, as can humic acids, like from peat.