I have been using a brand name float valve for auto top off in my sump for about 5 years. Well apparently they are only good for 5 years. Yesterday, I shut off my return pump and cleaned out my prefilter on my wet-dry, fired it back up and then we left for 7 hours to go to two birthday parties. Came home to a swamped living room. Apparently the float valve got stuck and kept filling and overflowing the sump. For now we have the tank taken apart and moved while we try and dry the carpet, padding, subfloor and the unfinished basement underneath. My fishies have been moved into other tanks for the time being. I haven't decided weather to keep the tank upstairs or move it down into the basement. Whichever we decide it sure won't have a float valve in it.