why is my overflow flushing?

[Fuzzy]

The reverse Durso looks like a really good idea.
Does anyone have some more pics?

The Durso's in our overflow are quiet - but the return in the sump is way too loud....
Our tank is a 150 w/dual corner overflows going into a 40 gal sump. The pump is a Velocity T3 feeding both returns - so I don't think I'm overloading the drains.
The goal here is to reduce as much noise as possible as the tank is in our family room.

Thanks

 

[dippin61]

<a href=showthread.php?s=&postid=9300530#post9300530 target=_blank>Originally posted</a> by celano
Just thought I would do a follow up for those interested or for those who do a search and find this thread.
Turns out that my return pump is WAY over rated for my overflow.
Its a Hydor pump rated for 900gph, after some more reading it turns out my overflow is only rated up to 600ghp. I dialed down my pump using the ball valve under the tank and now the overflow is working great. Just like it should be, no flushing.

I want to thank everyone that replied. Without your help I wouldnt have stuck with it and found the problem.
Thanks everyone!!

i was just about to ask what your return pump is, and that with a 1" drain, it can only handle about 600gph.

throttle your return back, and i'll bet the flushing goes away.

 

[cdbias2]

I think the Hydor is rated at 900 gph at 0' head. you are probably near a 5' head which should get it well within rang of the 600 gph overflow.

 

[Shnabbles]

when you say the over flow is rated at 600gph you mean per over flow right?

so if you had 2 over flows you could do 1200 gph?

 

[celano]

<a href=showthread.php?s=&postid=9317061#post9317061 target=_blank>Originally posted</a> by Shnabbles
when you say the over flow is rated at 600gph you mean per over flow right?

so if you had 2 over flows you could do 1200 gph?

Yes each overflow is rated for 600gph so if you had 2 that would be a total of 1200gph. But its my understanding(and I'm new at this so dont take my word as gold)that the closer you get to the 600gph mark the harder it is to maintain a constant lvl in your overflow.
Even with the head loss and some 90* elbows I had to cut back the Hydor so the overflow would work properly.

 

[dr_bull]

When I first set up my 150 I had a flushing effect coming from my durso overflow. What was causing it was the fact that I had a straight piece of pipe coming from the bottom of the tank into the sump. I fixed this issue by using a piece of overflow hose/pool hose and having it come down and making it curl into the sump. This way the water had a way to release the air that was in the pipe rather than having it go straight up the pipe again.

Before, notice how the pipe from the overflow is straight down into the sump:

After, this is a bad pic and I don't have another but notice the curl to the pipe now, it actually slopes down and curls back toward the corner almost making a full circle:

Hope this helps, i struggled with all the other solutions and this is the only thing that fixed my problem. It has been perfectly silent ever since with no water fluctuation in the overflow.