Wet/Dry Overflow

[Notsoballinxhobo]

If you T it off high enough it will break the water surface in the last chamber of the wet/dry, most of the ones I have seen will accumulate a protein skin at the water surface or detritus around the pump and have it T off and back into the last chamber will alleviate this

[Totenkampf]

technically, brian is right. putting backpressure on a positive displacement pump will shorten the life of the head seals. i can comment on this from a petrochem plant viewpoint, but not from aquarium experience so the shortening time may be negligible. its also true that we would design something like this to have a bypass flow back to the sump or else put an adjustable check valve in a line from the output to the input of the pump so that when back pressure starts to build it will vent pressure to suction.