If you let your water changes go to long the water quality drops fast and this could lead to the deaths of corals SPS go first then LPS and lastly softies except a couple like poles and Athenian and zoes. This is what I have seen in some peoples tank in the past, you can not get lazy in this hobby. You can put a water change off for a few days or a week but not much longer. I some times push it and my zoes close up this tells me I have to do a water change now. I like the little zoes as they let me know a few things.

Bill