Another drain/return question.
I see your return is lower than your drain and was wondering how you prevent back siphon? Or does the tank drain that much when the return pump is off?
Just wondering if a up and over return might be a better option for me? again less holes to drill.
The returns are low because they provide all my water flow and I want them in the best location to get the most benefit without being too high that they splash water or too low that they back siphon TOO much. That said they do back siphon a lot already and wish they were maybe a touch higher. When I kill the power manually I close a valve thats above the pump to stop the water from dropping to the lower bulkheads. If you look at the new hard plumbing setup Im thinking about doing, there is a wye check valve right before it Tees to each side. This is to stop the water from dropping when there is no power. But I also want to have a DC pump that could slowly push a small amount of water during a feed mode that would keep the pipe full of water. Either way the lose of water wouldn't be a problem.
The wye checkvalve is expensive but is important as it must be clean to function. My current sump has lots of extra water room so a checkvalve isn't required. It would make it slightly easier for myself but there isn't a lot of barb tubing valves that are reliable.
You can do over the top returns but you'd need an airhole drilled right as the returns enter the water or you'd still back siphon a lot of water. For me this setup provided the cleanest appearance, and the appearance of the tank and no visible equipment is very high on my priorities.