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Bubbles in my U-Tube HOB Overflow

I'm getting a bit tired of the every other day fuel tank technique of getting my HOB overflow started. Didn't seem to have this issue last year, now it seems it's often where there is a bubble at the top of the U-Tube causing my tank to overflow b/c the pump is doing its thing.

What are some good non gravity powered overflows and what can I do in the interim to solve the bubble issue?
 
they make u-tubes that are compatible with aqua lifter pumps (about $10 ) that keep a constant siphon going. thats all i know though, the rest is up to you to find out.
 
Is your flow of water enough to keep bubbles from building up? Is the filtration system, especially the U tubes.
 
Air usually accumulates there because of a lack of flow. If you increase this flow it pushes any air bubbles on through. I had this problem on an overflow. i had to increase the size of the return pump from the sump. If this is a new problem you should check your pump to be sure you are getting the right out put.
 

panmanmatt

Officer Emeritus
Officer Emeritus
Are you using a length of airline to remove the air from the U-tube? If so, do you leave it in place and what side of the U-tube is it on? Skimmer box or overflow box side?

If it is in the skimmer box side you will need to switch it to the overflow side. I set mine up in the skimmer box at first and the water flowing past it pulled air through the airline and was causing a bubble in the U-tube.

This may not be the case with you, but thought I'd share my experience with this problem.
 
* I'll look for a u-tube that is compatible with the pump.

* I have a mag9 pump which is more than what I need, I can open the ball valve to let more water through. The reason I don't is b/c the water level remains at about half way above the beginning of the overflow slits (tank side). I feel if I increase the return, the overflow box slits will be covered defeating the purpose of the slits.

* Overflow box on both sides has some dried algae that I can flake off if that's the problem...I didn't think of it, but I can actually take everything apart and clean it back to the day I brought it home.

* As for the airline; I break the siphon when I see a big bubble form, put in the airline on the overflow side and siphon to get the water flowing making sure to suck up some pods and other water creatures that are usually crawling around in the U-Tube...Mmmm..tasty.
 

Brian

Officer Emeritus
Officer Emeritus
I would clean everything out, if it was working previously, it should work again properly after a good cleaning.
 
In rereading the thread, are we talking about round, about an inch in diameter, U shaped siphon tubes, or those wide, long, sort of square, U shaped siphons, like you see on CPR overflows?

I have found those wide, square siphons to be a disaster waiting to happed, and have had multiple floods because of them trapping air bubbles, and breaking the siphon action. This occurred even with using of an aqualifter pump or a small powerhead to attempt to purge air to keep the siphon going.

The problem is that any small diameter tubing connected to the siphon can easily clog. This goes double for clear tubing, since algae can easily grow inside it. It's often not easy to notice if it clogs.

I found that switching to an overflow that used more traditional round tube siphons went a long war to solving the problem. If I ever replace the tank, it's going to be with a reef ready one.
 
My U-tube used to do the same thing. I drilled a hole at the exact top of the U-tube and superglue a airline flow controle valve in the hole and attached some tubing to it. I usually just let it hang behind the tank and whenever I saw a air bubble form in the tube I would shut off the return pump, let the bubble come to the top, put the end of the tubing in my mouth,open the valve, suck the air out, then tighten the valve back up. Once you do this you can also prime the overflow the same way.

I'll post a pic of what my U-tube looks like so you can get an idea.
 
That's an interesting setup. I think I'm going to purchase the pump as I'm nervous about leaving the tank alone unattended for days at a time. Don't think my neighbor wants to taste lovely live salt water.

It also seems that cleaning the tube, increasing the return, and cleaning the tank side box has helped the situation. I haven't had an issue since. Fingers crossed.
 
1320wrx said:
My U-tube used to do the same thing. I drilled a hole at the exact top of the U-tube and superglue a airline flow controle valve in the hole and attached some tubing to it. I usually just let it hang behind the tank and whenever I saw a air bubble form in the tube I would shut off the return pump, let the bubble come to the top, put the end of the tubing in my mouth,open the valve, suck the air out, then tighten the valve back up. Once you do this you can also prime the overflow the same way.

I'll post a pic of what my U-tube looks like so you can get an idea.

You could also just run the tubing to the venturi attachment of a maxijet (if you use one) and it will continuously pull out bubbles from the u-tube.
 
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