Need some help with my overflow

[number1gsxxr]

I have a hang on back overflow that has been working fine since I setup my tank about a year ago. Recently something has occurred to cause the water level in the tank to rise quite a bit and I have had it overflow once already.

Here's my setup: I have a Mag 5 as my return pump and some brand of overflow that came with my sump.

The back chamber of the overflow used to have a cylindrical-shaped foam sponge filter as a means of keeping fish/snails out of the sump but I removed that since it looked like it was getting clogged up. I replaced it with a plastic pvc guard w/ slots in it. I figured all was well until the water level started rising again. The next culprit I thought might have been the sumps filter socks. I tried replacing them with clean ones like I usually do every 2 weeks and then ultimately removed them altogether. The water level still rose.

If I turn off the return pump momentarily and let the water level-out again, it seems fine for a few minutes, but then starts creeping back up. It seems like the overflow tubing is somehow clogged and not flowing as much as it used to or the return pump has somehow become stronger and is pumping more water. I don't know what else it could be.

You can see how much higher the water is based on the coralline algae on the overflow. Also the sump water level is much lower than where it usually is. It usually stays right at the bottom of the blue tape.

 

[shawn]

The idea of the overflow is that water should "overflow" into it on the tank side - not have it completely submerged. If it is completely submerged you won't get any surface skimming action. Is there some kind of constriction or blockage in the tube from the outside of the overflow to the sump? That tube should flow freely such that it has more flow capability than the return pump. From your pictures it would seem that it isn't keeping up. One thing to check is that you keep the bottom of that tube submerged in the sump. If not, air trying to move up against the downward flow can cause it to slow down. Also, I can't tell from the picture, but is there some sort of filter on the top of it? If so, make sure it is very clean (or remove it entirely - if it gets that far, let it go down). Or if you did remove some filter material ahead of it, that filter be clogging more quickly than expected.

 

[shawn]

Oh - one other thing - make sure you don't have the problem of air build up in the "U-tube" from the inside of the tank to the outside.

 

[shawn]

Sorry for the rapid fire posts - but is the water level inside the tank higher than that in the part of the overflow outside? If so, it is the "U-tube" connection that is the problem. If not, it is the tube from the outside down to the sump that is the problem.

 

[number1gsxxr]

I took that pic to show how high the water is. Normally it is not above the height of the overflow. I understand the concept that the overflow should always be able to drain more water than the return pump can pump and I thought I designed the system for that. It also had worked flawlessly for almost a year now.

I flipped that black pcv screen upside down and that seemed to help. I'll have to keep an eye on it still. It's a major pain not knowing if/when it will overflow again.

 

[stingythingy45]

There's something in there.
Sure as #hit.Have you run anything down the overflow line yet?

 

[jamesdong009]

There's something in there.
Sure as #hit.Have you run anything down the overflow line yet?

I'm gonna agreee and say that algae/detrius is slowing down the flow.

 

[number1gsxxr]

I'll have to snake something down it then. It's that ribbed spa type hose. Any ideas what would be a good tool to jam down there?

 

[stingythingy45]

I'll have to snake something down it then. It's that ribbed spa type hose. Any ideas what would be a good tool to jam down there?

Either a plumbers snake/electrictions with a hook.
They're not much,and will add to your tools.........hu rah...rah.........ugggggggg!
Just don't tell the wife.

 

[number1gsxxr]

I ran a coat hanger down the hose and twirled it all around. I even took the hose apart and looked through it with a flashlight and it's very clean inside.

What I ended up doing was use an Aqua Lifter pump to suck out a very small air pocket that was in the U-tube. This seems to have done the trick but I will continue to monitor it. The air bubble was so small that I can't believe it was impeding the flow enough to cause this to happen.

Thanks for all the suggestions. I should have paid more attention to the U-tube but the air bubble was so small that I dismissed it. Hopefully this fixes it and I know what to keep an eye on now.