Noisy overflow? Flushing noise? Creative solution for you!
OK.. just had the EXACT same problem. Two things I did differently. Mostly since it sounded like someone flushing the toilet in my dining room every couple minutes.
First. Get a ball valve on the return lines near the bottom of the return. I slowly adjusted mine until I didn't have the flushing noise. PLUS it cut back the bubbles as well.
Second. I got creative with filter with a power head part. Flipped it upside down and plugged right into the hole. Played with the valve again until the water was constantly flowing to the TOP of the filter.
NOTE: I've seen some custom builds on the net of folks using 90deg PVC
elbows to cut down that noise. Not sure how they do that myself.
75gal Salt, 18gal Sump, Skimmer, 60lb Live Rock, 90lb Live Sand, 3 Pwrhd, 2x55w Actinic, 2x55w 10k. Guest list: Goby Green Clown, Percula Clown and entire clean up crew.