My understanding is that calcium will only raise Gh and therefore shouldn't affect Ph. The carbonate in the calcium carbonate will affect Kh and Ph. Maybe something else is going on?
CaCO3 increases pH to 8 – 9Limestone (CaCO3) lowers PH... fyi..
I guess it's the CO3 that did it..
Then it is not Calcium sulfate CaSO4. Calcium sulfate does not change pH.Everytime I add calcium, the PH goes up a little.. Is it possible to have it not go up...
I have added gypsum (calcium sulfate).