It is typically not a good idea to use crushed coral for a substrate. however, many people still do it, especially with their first tank...some are even advised to use crushed coral by their LFS... I almost went down that road, but the guy selling me the tank, etc. wouldn't let me buy the tank if I didn't by the right kind of substrate. Sorry, didn't even notice that this AM. As your tank is having some problems cycling, you might want to consider swapping it out... in the long run you will be much happier.