For people with tanks drilled for return lines:
How do you keep the water from pouring back into the sump during a power or pump failure? Do you just make the return pipe rise above the water level and before connecting it to the return bulkhead? Or is there some kind of check valve that can be used? Or just nothing at all?
How do you keep the water from pouring back into the sump during a power or pump failure? Do you just make the return pipe rise above the water level and before connecting it to the return bulkhead? Or is there some kind of check valve that can be used? Or just nothing at all?