Make sure you al are testing for Calcium if you are using this product, especially if you are using it with another Ca supplement.  All it is is a different form of Ca... just cant remember which it is.  IMO, you should use Kalkwasser for Ca and maintain a Ca level of around 350-400ppm ALONG with an alkalinity level of around 5 meq/L (~14dKH).  This is the best way to get good coraline growth. 
HTH,
Jesse