I have a 6ft long 125g reef. Been up and running for almost a year now. I have drilled overflows on each side that both term into a dual sump located on the right bottom of the tank.
Both Dorso's have a pin hole in the top of them. They both seem to be "suckinig" water efficiently. The one on the right has the water level right where it is supposed to be - on top of the "T".
Prolem is dorso on the right has, and always did, have the water level right about the air hole-- way too high. -- but it is still sucking fine out of the T.
This has always been a problem but now I notice stagnant water on the left side of the tank all around the overflow box... like the box isn't sucking enough water into it. I NEED TO FIX THIS.
I have tried covering the pin hole in the dorso and the water level doesn't really go down.... im pretty sure widening the hole won't solve the problem. So i'm thinking its the plumbing on the bottom of the tank. Since the dorso on the right has the sump right below it - i'm thinking that the problem with the left dorso is maybe because the plumbing on the bottom has to travel 5ft to the sump on the right and then enter a 2 1/2ft flex tube to enter sump.