Have you had an algae bloom? A proper water change is never going to hurt anything, in the beginning I do them once a week. Cleaning crews need something to clean so if you haven't an algae bloom then adding them will just kill them and cause the tank to get worse. A week is pretty quick for a tank to cycle unless you put live sand and a ton of live rock in it. I have about 1 lbs per gallon of live rock and 1/10th of tank is live sand. I had an algae bloom at exactly 7 days. I still haven't got clean up crew yet I'm at about 14 days now. Going to get a couple little guys today though. I put one clown fish in at day 2-3, more for my wife to stop saying I want this and that and those when we went fish shopping. You have to make sure whatever you put in the tank it has a food source, not everything eats fish food. Once you see little bug looking things crawling everywhere in the tank that's when I consider it established personally.
