Once, while being rushed by my wife, I accidently left the drain pipe from the overflow behind the sump after doing a cleaning of all the pumps and tubes. I turned the power strip back on and ran up stairs and started to getting ready. After a few minutes my kids came running up stairs to tell me the tank was leaking all over the floor. You can imagine how fun the rest of the day was. Take your time when putting everting back together after maintance, Trust Me.