I have a 29 gal freshwater tank that has (1) 12" black knife ghost, (1) 5" rhino plec, and (1) very large angel fish. I want to change out my current substrate which is the natural colored gravel to white crushed coral. Is this going to be a bad thing for my fish? I have a small 10 gal tank that I've already changed over that has a 2" rhino plec and a couple of smaller glass fish....they seem to be doing fine.