What causes noisy overflow

[marino420td]

I'm looking for a scientific explanation of a noisy overflow. What causes the flushing sound? Gurgling sound?

I know about the durso and stockman standpipes and such and I'm not looking for these items in this thread. I just want someone to explain what conditions cause this noise.

I will use this information to troubleshoot my new system.

Thanks.

[Rock Anemone]

I believe it (atleast with mine) is due to the air that is trapped in the overflow pipe. I can fix mine most of the time bu placing a small flexible tubing down it to release some of the air.

Rock Anemone

[jayo]

water mixed with air, moving quickly, is noisy as the water is able to crash into things (pipe walls, more water, etc).

fill a jar all the way to the top (no air), cap it, shake it, no noise!

fill a jar halfway, cap it, shake it, super noisy!

the various ways used to quiet overflows have two basic strategies:

a. no air in the overflow - silent
b. air+water moving in a controlled fashion - like the half full jar, which is perfectly silent when you arent shaking it around :)