I wanted to use a stockman standpipe in my new frag tank, but I didn't want some box with square corners messing up my flow I got around this by using a 9 7/8" piece of 4" PVC, a 4" end cap and a 1" bulkhead. The end cap drilled out for the 1" bulkhead and glued to the tank bottom. Then the body is glued into the end cap making a round 4" overflow with a water line up just above 10". Add in the stockman standpipe, and you've got a silent overflow. I'm adding a bit of black 1/4" mesh aquaculture screen on the overflow to stop any larger debris from enterring the overflow.