Help! Overflow not working

[Tervill]

Hello everyone,

This past week I have been setting up my 90 g, and I have run into some trouble with my overflow sysyem. This is how it is set up: I have a hole drilled in the back wall of my tank with a screened bulkhead. The center of the hole is approximately 2.5 inches from the top of the tank. Attached to the bulkhead is a 1 inch hose going down to a 15 g sump tank. In the sump, I have a Mag Drive that is pumping aproximately 400 gph through a 1/2 inch hose back to the main tank (I am installing 2 powerheads so the total flow is around 900 gph). Here is the problem: The amount of water flowing into the sump is not equalizing with the amount of water that is getting pumped back into the main tank. In other words, the water is not draining fast enough to keep up with the pump. I find this strange seeing how the overflow tube is 1 inch dia. and the pump tube is only half inch . However, when the water is flowing down to the sump, air is getting mixed in with the water and causing a "bubbling" efect. This air is comming from the top of the screened overflow until the water level raises above the screen, where, in turn, it keeps on rising until my sump is dry. I had the 1 inch overflow line submerged in the sump tank at first, but I thought that this was causing the water restriction, so I cut the tube shorter so it would just fall into the sump, but this did not help at all; in fact it actally made is worse (plus the sound of the water splashing would drive me and my wife crazy).

I have seen this type of overflow before in magazines and books, and it seemed to me like a no-brainer for setting it up. I hope someone out there could shed some light on this problem of mine. Thanks in advance for any help

[Reefland]

Hi Tervill!

Well, bubbles are bubbles and your not going to find a way to stop them from entering your drain pipe and making it to the sump. The only thing you can do here is make sure once in the sump, they don't make it to the return pump and your tank.

As far as the water not equalizing, logic would seem to allow it. The tank is not overflowing correct; it is just fluctuating? This is the same thing that happens to the water level inside a corner overflow or a surfce skimmer connected to a prefilter box. I think an easy fix would be to get a surface skimmer made and hooked up to your bulkhead and see how that does. The only problem I see here is your bulkhead may be too high to do this.

Scott Z.

[Tervill]

Hi Tervill!

Well, bubbles are bubbles and your not going to find a way to stop them from entering your drain pipe and making it to the sump. The only thing you can do here is make sure once in the sump, they don't make it to the return pump and your tank.

As far as the water not equalizing, logic would seem to allow it. The tank is not overflowing correct; it is just fluctuating? This is the same thing that happens to the water level inside a corner overflow or a surfce skimmer connected to a prefilter box. I think an easy fix would be to get a surface skimmer made and hooked up to your bulkhead and see how that does. The only problem I see here is your bulkhead may be too high to do this.

Scott Z.

Scott... Thanks for the reply. Do you think that if I attched a T coupler on the back of the bulkhead, put a cap on it, and drilled a hole in the cap would increase water flow by letting more air into the hose? The tank water level isn't fluctuating... it just goes up, then I have to shut off the pump and let the water drain back into the sump. Do you think I should have the overflow tube submerged in the sump water, or let it fall in? (Man, this is frustrating.... but it's still an awsome hobby!)

Terry

[rayjay]

From the way I read your post, the outflow just doesn't equal the inflow from the sump.
In my opinion, you will never get enough flow down the 1" overflow, to handle the kind of return flow you have, even though it's only 1/2" dia..
The outflow is only gravity powered, whereas the return is mechanically powered, enabling the higher return flow.

[the_blue_tuna]

My guess would be that the screen is too fine and its causing restriction in the water flow. Can you remove the screen and then give it a try ? If it works then , you will need to find a larger screen or come up with a different method for keepin out your critters.

[Tervill]

It worked!! I drilled a small hole (1/4") in the top of the bulkhead (back) to allow more air flow into the system. The inflow and outflow are now equalized. The only problem now it that there is a constant gergling noise comming from the hole that I drilled . Does anyone know a way to stop this noise??? I think a type of silencer might work, but is there such a thing out there?

Terry

[Poseidon]

use one of those 35mm film cans filled with filter floss, drill a hole in the bottom, leave the cap off get some rigid tubing from the LFS and use that to connect the film can to hole u made in the back...

Imagine a Film can on a stick...

that should "muffle" the sound, another trick is at the bottom of the drain I used 2 90's so the water exits facing up, it really helped with the bubbles going into the sump...

Mike

[Tervill]

use one of those 35mm film cans filled with filter floss, drill a hole in the bottom, leave the cap off get some rigid tubing from the LFS and use that to connect the film can to hole u made in the back...

Imagine a Film can on a stick...

that should "muffle" the sound, another trick is at the bottom of the drain I used 2 90's so the water exits facing up, it really helped with the bubbles going into the sump...

Mike

Thanks Mike... I'll give it a whirl.