Help removing air bubbles from U-tube overflow

[number1gsxxr]

I've been using an overflow box for a while now to get water to my sump. Recently it has started to collect air bubbles at the top of the U-tube at an alarming rate and a few times I've caught it just in time before my tank overflows. It's a huge pain to start the siphon over again and remove all the air.
I've seen those continuous siphon overflows but A) I don't want to buy a new overflow if I can help it and B) I don't know how I feel about trusting an AquaLifter to maintain siphon.
Does anyone have any ideas to remove the air bubbles? I was thinking something along the lines of a radiator bleed valve but I think those are made of brass.

 

[veni vidi vici]

I would try slowing down the flow rate by regulating return flow.
When i had a HOB overflow I would use 1/4" tubing to start the siphon and then i would just leave one end of the hose in the U-tube and then drop the other end into the water.If and when I needed to remove air buildup,all i would have to do is pick the hose out of the water and suck the air out.

 

[nemo22]

what size is your tube? i saw on you tube, someone had the same problem and he got a smaller tube and the air bubbles stopped. check it out if you can.

 

[number1gsxxr]

On another forum I'm on people were saying to get a bigger return pump. They were saying the greater flow would take care of the bubbles.
I've used my Aqua Lifter that I use for dosing kalk to suck out the air from the U-tube but after a week or so the tube is full of air again and losing siphon. It's a pain to unhook my kalk setup and then have to set it up again.
I think a smaller tube increases the flow. I think I have about a 1" U-tube. I can take some pics and measure it later.

 

[number1gsxxr]

What do you guys and gals think about this advice?
"The easiest fix without changing the flow rate is to drill a small hole at the very top of the U-tube, just large enough to fit a small length of rigid airline. You want to glue this piece in place, just allow it to penetrate the thickness of the U-tube, if you go to deep you never be able to remove the bubble completly. Use some scraps of acrylic to make gussets for extra strength.
After it has dried add a decent length of silicone airline, a control valve and another lenght of the silicone airline. Make sure you get a quality valve. Now you just open the valve slowly while sucking the air out of the U-tube, watch for the U-tube to fill completely and close the valve."

 

[cranberry]

That's fine advice for getting the air out, but what if you aren't there to remove it?