If you use a Herbie, it should be close to silent. I've spent a ton of time reading about it on RC. (I'm going that route on my tank too).The stand pipe should be about half way under water in your overflow and form a silent full siphon. Generally they have one of those pointed screen fittings over the end. And your emergency should be totally dry and slightly over the overflow water line. So no noise from that. Key is a gate valve to dial in the full siphon.