I drilled two 1/8" holes into my return line as siphon breaks. When I simulate a power outage, the holes get exposed and suck in air, but the return line doesn't stop flowing until the open end of the return sucks in air. I'm guessing that the holes arent introducing enough air to break the siphon but I fear adding more or larger holes will dump too much water volume into my overflow and hurt circulation. Finally where do most people point there return nozzles? Along the surface to help oxygenation or down to provide more even flow to the rest of the tank?