Originally Posted by
Clawhammer
A fishless cycle is a good time to test these things. My tap water is <1 dKh, I find crushed coral has very little effect because of frequent water changes (70% daily for grow out). I have about a half cup of CC in my canister and my Kh goes from <1 to between 1 and 2dKh and the pH is unchanged by the time of my next WC (24 hours). If you are keeping your tank clean and doing frequent WC's (when you add fish), I think it isn't necessary. I am contemplating removing it from my filter