I have a 40 gallon Brute feeding my sump ATO. Problem is, when the ATO turns off, water continues to siphon into my sump (when the water level is higher in the Brute than in the sump). Came home yesterday to find my salinity at 30.4. I've thought of using a solenoid valve powered from the same outlet as the ATO, but have read that they do not fully close absent pressure (when they work at all). I'm sure there's a simple solution but it eludes me. Could use some suggestions. Thanks.