found standpipe doesn't make any different in the overflow chamber level (I can remove it and level just stays the same). The only effect is see having it, is the amount back to sump with pumps off or if too high, I'll start getting a vortex and suck in air.
What effects the chamber level is back pressure on return line, by how the valve is set or even if my filter sock gets dirty and water starts rising in the sock. If you are going to play, maybe do so on how deep the drain line goes into the sump.
Ended up run my main drain chamber high so water drops probably less than 1/2 an inch so really no noise.
