Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Always include the units. GH and KH are measured in several formats. I assume you are reporting German degrees of hardness?
Neither GH nor KH should be that high (10-15 degrees) with your fish list.
GH for most of those fish are in the single digits, I would say 3-9 is probably acceptable for them (though you should look up each fish and check the optimum parameters, including temperature)
KH should be at whatever level it needs to be to maintain the optimum pH. Often the water company will add something to the water to keep the pH up. Acidic water is bad for the pipes. You could add some peat moss to see if that will lower the pH.
When in doubt, if the KH = GH plus or minus a degree or so, that is usually a good target to aim for.
I would not try to alter the GH or KH in this tank, with these fish.
Are you also adding a bit of magnesium? Plants use calcium and magnesium in a ratio of about 4:1. The water does not have to have this exact amount, but something close would be good.
GH and KH are separate tests, and check different things. No need to combine the results.