Noisy drain to sump

[Lampshade]

With a filter sock on the output you'll be fine for bubbles, I was running without them, so the bubbles freely travelled to the return. After lots of fine tuning the duroso was quite, the bubbles on the output where louder than the intake of water at the top. I swapped to a single herbie instead of my 2 duroso's, if you have that ability I'd recommend it.

Also, if the main input to the duroso is getting air you will have a loud bubbleing, i used a 90 and brought the intake down 4" under the water line, it was well needed, stopped large bubbles, only had smaller ones from the air intake.