I took one of mine apart to clean it-the first time I've cleaned it since I've owned it (about 6 months or so); and ever since I put it back in my tank-it's making an awful noise! sounds like an airplane about to take off-(ok, not quite that bad, but really annoying); any suggestions? I am assuming that I didn't put it back together correctly---I soaked it in hot fresh water and took it all apart-any other tips?