Overflow questions

[Dozer]

Ok, I'm confused and would love some help if you all can. Here's the deal. My display is 125g, about 25g more in the sump/fuge. I'm using a dual overflow box to drain the water from display into the sump/fuge. Basically this one: http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW

For my return pump from sump/fuge back to display, I'm using an Iwaki MD 30RLXT - this one: http://www.premiumaquatics.com/Merch...ory_Code=Iwaki

Now here's my question. If the overflow box is rated to drain about 1200gph, and my return pump is rated to return about 960gph, why in the world am I having to throttle back my Iwaki? Not just a little, but I actually have to close it off quite a bit with a valve- I would estimate at least 1/3 of the output has to be throttled back or redirected back into the sump. If I try and run it wide open, it just starts draining the sump really quickly- meaning it's leaving the sump faster than it's coming down into the sump. Is there a scientific reason why this could happen, or is there more of an art to the setup that I'm maybe not doing right?

Obviously if I was to leave it wide open, and then just dump makeup water into the sump as it drains, it's just going to ultimately flood the display, right? I guess I'm wondering if something "magical" will happen (lol) and it will level itself out somehow in a way that I'm missing, when I add more water. But logic says no, I'll just keep adding more water and the return chamber in the sump drains, and it will eventually flood the display because it's returning more than it's draining.

Any ideas/thoughts would be appreciated!

Btw, it's not a brand new setup, it's been this way for a while, I just teed off the return line and let some of the return flow divert back into the tank. It's not that I can't continue to do that, but I started thinking about it and it just bugged me that the numbers don't add up. I should be able to run the return wide open it seems to me- which would also give me a little more flow in the display which would be nice.

[Ed]

Are your drain lines in the sump above the water level or submerged? Sounds like a silly question, but if they are submerged it will definitely drain slower than if they are above the water level. Just a thought.

[gjuarez]

Hey I didnt know that. Thanks Ed.

[GaryP]

I had the same thing happen to me when I put in my PanWorld. I added another single return and now I have replaced the double and single with a quad overflow box. I just wish I could go out and buy a new RR tank.

[Dozer]

Ed- thanks for the tip! In fact they are underwater. I guess it's a choice between noise and efficient drainage. Hmmm...

Gary- In your case did the numbers also not "add up"? In other words, is your quad rated for way more flow than your return pump?

[Ed]

Glad I could help. ;)


Mike,

Don't know how your sump is set up, but if you can terminate the drains just above the water level or break the fall of the water with something (live rock rubble, bio balls, filter floss on a piece of eggcrate, etc.) the noise level can be greatly reduced.

HTH.

-Ed