If you're still getting diatoms, you may be feeding too much or too often...your corals don't have to be fed everyday, that will mess your water quality up. Also, what do you feed your tank...how long has the tank been set-up, and do you use ro or tap water. These are a few questions that will help us locate the source of your problem. Yeah, I nice cuc will clean your tank, but we need to find the reason why you're having the problem in the first place...sorry that it may seem like were taking too long to answer your post, but you have to be patient with us, and realize we all have jobs and families...this is a hobby of great patience, that we all must exercise to be successful.