I made my own durso standpipe. Works great. Overflow chamber is nearly silent now. This has created a new problem, however. The water draining into the sump from the standpipe is water mixed with lots of air. This makes for a pretty loud sump as the air escapes. I have a 90 gal
with a sump that is about 15 gal
Setup #1: 3/4" PVC
with an elbow that dropped down into the sump and another elbow to run a horizontal perforated PVC
pipe under the water. Extremely loud. A lot of the noise was just turbulence within the piping.
Setup #2: 1-1/4" PVC
with just one 45-degree elbow leading to underwater perforated pipe. Much quieter, but still way too loud for an aquarium in the living room.
My perforated PVC
is basically a super highflow airstone that causes a rolling boil.
Surely someone else has had this problem and found a quiet solution.