non flowing overflow

[tony7855]

I have a 180 gallon tank with two corner overflows. The pvc pipe on the drains dont seem to be letting water flow through. They have the straight pipe going from the bottom of the tank to the top. The top has two 90 deg. elbows on top turning the pipe back into the water. There are two holes drilles on the sides of one of the elbows and a hole in the top. The water drains through the little holes but its not enough. I can watch particles float by the grates of the overflow and not go in. I took the elbows off and it worked wonderfully. Only problem there was that it was way too loud.

Any suggestions as to make it drain better without it being soo loud?

Thanks

[sirreal63]

Post a pic of the elbows that shows the holes.

[Darth Vedder]

Sounds like a durso, the adjustable ones have two holes on the side to break the siphon. Is the water level betting high enough for it to start to create the siphon and then lower when the pumpe are on? It should be a tad lower that the water level in the tank or it may not fill enough to start the siphon and is only draining through the holes meant to break the siphon when the pumps are cut off