Plumbing issue

[gregzz4]

Maybe you could try open-topped standpipes, and use a gate valve to adjust the height above the pipe

My chaeto tank has this and, with the water about 1" above the pipe, it's silent and no bubbles. If I lower the level below 1" it will suck air
And, of course, the drain is under water in the sump

The valve doesn't noticeably slow down any flow - it only adjusts the height

The pipe on the right is an emerg overflow