[liveforphysics]

I'm glad you aren't having vortex problems Bean. I think you are saved due to the chaos of the water motion entering the overflow area. Even if you did, generaly a disk of plastic above the pipe can avoid them, and that would be simple to retrofit.

From a velocity and noise perspective, I think valves near the end of the pipe would be optimal, it wouldn't require the use of those beautiful tru-union valves which would reduce plumbing cost as well.

This sort of system is absolutely superior to all the durso/stockman/gurgle buster style techinques for getting a tank to be quiet. After people hear how quiet a large reef can be when they come over, they are generally stunned and wondering why there own tanks 1/4th the size are so much louder. Silent overflow designs are the most critical part of getting your reef whisper quiet.

Anybody looking for a silent tank should take a serious look at Bean's excellent design before plumbing. The herbie method and this method both can yeild you a silent tank, but Bean's method can handle a huge amount of flow with only small pipes and bulkheads.