overflow too small?

[Safir]

I have a single u-tube overflow, and I think I am moving too much flow for it - if i try to turn up the return flow to teh tank the water lever in the drain portion of the overflow begins to oscillate, causing it to gulp in air and make a lot of noise/bubbles in teh sump - if i turn up the return any more the oscillation becomes worse and the water level in the display starts to rise.

I suspect That my oerflow is undersized for the amount of return flow I am trying to move, but have not ruled out something stupid I am missing.

[asmujica]

Have you tried the bulkhead calculator here on RC?

How much flow are you pushing?

Sounds like a Durso standpipe may solve your problems.

http://www.dursostandpipes.com/

[Safir]

durso standpipe won't fit in my external overflow - stockman standpipe doesn't help - this is a matter of not enough water going through the u-tube. without a standpipe i get the tilet flushing noise and the gurgling/surging - with a standpipe all i get is the surging - eithe rway the display continues to fill until it reaches the rim and i turn back the flow to save my carpet.

as far as flow, i've got a MAG 5 with a fair amount of head pressure (~4' and 4 90's - 1" return teed to two 1/2" outlets - it's 1" all the way to the outlets

it really seems the bottleneck in the system is the u-tube, if i pull my standpipe out of the outer box it drains immediately, telling me it can handle the flow

[asmujica]

Maybe you need to change the overflow... :(

[Safir]

thta's waht i expect - LFS owner said it would be a good size for my tank and it didn't occur to me to ask how much it flowed - my own fault I suppose.

*goes in search of a decent 600GPH overflow at a low price*

[asmujica]

Lifereef makes some good overflows. But I haven't been researching overflows lately so maybe you will have better luck with the search engine.