air in U pipe

[kvv711]

I was wondering if anyone ever had this experience. I have an outside overflow that works fine, but it seems that every once in awhilw, the u tube seems to get air trappen in it, and the flow decreases. I added a second U tube, but it still happens.
I checked the tubes for leaks (both air tight), and I have no bubbles in the tank. How could these tubes be getting air into them?
Thanks

 

[magnus042]

whats most likely happening is micro bubbles in your tank are accumulating in your u-tube. a simple solution is to take a powerhead withe a venturi attachment and place the end of the airhose at the top of the u-tube. not only will this clear the existing air, it may help in the event of a power failure.

 

[mpls man]

one thing you can try diong is placing a piece of foam in the overflow box in the tank , this will stop the micro bubbles from going into the u tube, just make sure the foam doesent get in front of the tube, i did this and it worked well, but you have to clean the foam when it gets dirty.

 

[newty]

as magnus042 stated, drill a hole at the highest point of the u-tube, and attach it to a powerhead. you do not need to keep it attached all the time. i simply have a hole that is sealed, and whenever i notice that there is air bubbles accumulating, i hook up a venturi line to the powerhead to get rid of the bubbles. once the bubbles are gone, i remove the line.
newty.

 

[spline9]

Every once in a while, when I take out my overflow box and have to restart the siphon, I'll sometimes get an air bubble in the U tube. I just get a piece of paper towel and let the siphon suck it up in the overflow. The towel will catch the bubble and carry it out the other end. Just make sure its not a big piece and block the U tube. Heh.
I do like newtys method, though... Might have to give that a shot.