Noise elimination without constant tweaking is fairly straightforward, but you have to have 2 pipes. Pipe 1, with a valve, runs in full siphon mode, and takes 90% of the water. This one starts at the bottom of your overflow, and exits under the water in your sump. Being in full siphon, it is 100% dead quiet. You need the valve to adjust the flow to get near that 90%. But rarely needs tweaking after that. Pipe2 starts very high in your overflow. About 2" down from the top. So acts a bit like an overflow, inside the overflow. (Or, do it durso-like, but does not matter much) It also needs to exit under water in sump, but needs some sort of small vent hole, to prevent suction. This only takes 10%, and with such a small amount, will have mostly laminar flow on the sides of the pipe, so will also be very quiet. You can run it slightly off vertical, and it gets even quieter. Do that, and your powerheads will make more noise. Reduces bubbles as well.