Bubbles in overflow U-tube

Where are these bubbles coming from? They are collecting at the top of the U-tube and will undoubtedly cause the siphon to break over time.

Play the video for a visual.

 

Stick some airline tubing all the way up the tube while it is submerged. The end of the airline has to go to the very top of the bend. Suck all of the air out of there and it will hold a syphon. I ran one just like this for a very long time. You could also do as mission said and put a nipple on there and use an aqualifter

 

I got all the air out, but it slowly collects.

 

Definitely an option I may have to pursue.

 

I have has that problem. The problem comes from not enough flow going through the utubes. When I dial downy return the utubes start to collect air bubbles.
If you can increase the flow that may be a start. If you cannot then you can try the above suggestions.

 

Overflow boxes are terrible. Only fanboys and liars prefer them over a real drilled tank.

 

Maybe I'm not understanding what's a fanboy?
I must agree with you though. I wish I would have drilled my tank when I got it. I didn't because I didn't know to much about the sump/ overflow aspect of it since I came from a tank with all hob equipment. But since its too late to drill I am making due with what I have.

 

This.
I have my flow cranked up pretty high.
Even the smallest of bubbles get yanked right thru the u tube, no chance of them collecting.

 

Thanks everyone. I sucked all the air out after turning on the pump. It's good now and not collecting bubbles; they shoot right through.

This tank was set up a year ago. Couldn't drill it.