if by white spots you mean ick or ich however you want to spell it. there are a number of medications at the lfs. also you can try hyposalinity which is bringing the salinity down slowly until you reach 1.014 and leave it there for a couple weeks. will not harm fish but if you have inverts it will kill them as well. this will not hurt your fish. i've had it lowered for several weeks and none of my fish ever died and i was even lucky to not lose inverts as well.