My new 125 tank will not have Speer. valves. There might be a bypass valve in the sump for circulation but that is all. I had it drilled close to the top of the tank.
The sump and the tank will be approximately the same height.
I intend that the return water from the sump will go to the bottom of the tank first and up through an undergravel filter and a coarse sand bed. The pump in the bottom of the sump will be at about the same level so there can be no back siphoning.
If I put a bypass valve on the pump however, I can back-siphon at that point anytime I want.
If I put two valves and a loop on the pump I can make it pump the water in or out thus not relying on a gravity siphon.
I'll bet no one here has ever done a sump like this before.
