Since I have a turtle tank I was wondering if this could be possible? I was thinking of adding a slit in the PVC
wide enough to cause an interruption in siphon, but still allow for most of the flow to come from the original opening at the bottom of the pipe. The idea is that when the water level reaches my main surface overflow, the bottom skimming overflow slit will also be at the same level, in which air will enter the PVC
and interupt siphon. So I'm talked two overflows here, one for surface and one for bottom. Really trying to design a sump system that will accommodate heavy turtle waste. There has to be a way! Ill try to get an actual design posted incase I'm confusing anyone.