i opened the overflow valve completely, and set the pump valve to a point in which i know the overflow has no problem keeping up. I then closed the overflow valve just slightly to bring the exit chamber water level just over the baffle and it seems to be holding. exit and intake of the overflow are also whisper quiet. The intake is just beneath the water and isnt picking up any air or bubbles from the surface. I guess ill try it like this for 24hrs and hope the levels dont change. (im running an ATO in the sump)

Keep an eye on it, you might have just found the sweet spot.

noisy overflow??
 

make a durso inlet. check out this link

http://www.rl180reef.com/180/pages/s.../construct.htm

i made one and it works pretty good. no noise.

its a DIY and it is easy to make.

when you make one let me know how it goes.

:laluot_14:

This is not an option with a CPR overflow box.

I have the same overflow only my problem is not big enough pump and I have to keep the overflow throttled back quite a bit creating excessive noise hoping once i get a bigger pump it will quiet down also because of this my waterlvl in the exit chamber of the CPR is only 2-3" not even above the foam of the bulkhead

Me too I need a bigger pump mine can't pump up fast enough
 

I can't understand why you would want to buy a new slower pump if you can adjust yours down. Sounds like you found the way to play with it.

I had mine running like that for awhile. I was more comfortable having that chamber as low as it was and not having to worry about overflowing in that chamber if the water level in the tank started to creep up. I couldnt take the noise coming off it though, and the air breathing tube didnt appear to help at all with the water level in that chamber so low.

Hahahahaha I laugh because I actually caved a night or two ago and toned it down couldn't take the noise any longer now it's fairly quiet