Overflow "U" tube has air bubble that won't go awa

[spinman]

One of my dual overflow upside down "U" tubes seems to want to maintain an air bubble that in the past has gotten bigger and broken the siphon. Funny thing, the other "U" tube doesn't have this problem.

I've tried shaking the tube, but no change. I've tried to pull the tube out and restart the siphon, but that little air bubble remains.

Thoughts?

Mike

 

[Salttanker]

I had that problem prior to going built in. It never went away, and I would always have to siphon to get it going. I hated having to mess with it.

Mike

 

[Brodie]

Jiggle the U Tube. Bring it up and down, and just clack it around. Just make sure you don't break the siphon. It's really easy, just takes some time to get it out.

 

[fishyrican]

You could try to suck it out using an air hose. Just insert the air hose into the u-tube and suck the bubble out.

 

[fishfreek]

A DIY remidy is to first purchase a spair U tube for your overflow. Take that U tube and drill a hole at the very top of the bend. Insert a push on air hose nipple and seal it with sylicon so its got an air tight seal. Then attach a lengh of airhose to the U tube and put a powerhead like a Maxijet 600 or 900 or even 1200 in your tank beside your overflow. Insert the other end of the air line into the ventri port on the powerheads outlet. The flow from the powerhead will keep air out of the U tube.

Test this setup in a power off setting to verify things work properly with the startup of the syphon, etc.

 

[jaiden]

aqualifter is designed for this.

 

[bigsky]

How many gallons per hour is your return pump returning to your tank?
You may not have enough flow to use 2 siphon tubes because it sounds like you don't have enough flow to push the bubble out. Does it run fine with just the one tube by itself? If so just run one tube.
My tank's return is rated at 350GPH @ 4' head pressure
and I use one 1" siphon tube.

 

[spinman]

Maybe Bigsky hit the nail on the head. The one good "U" tube does seem to handle the flow on its own when I have the other tube out of the box playing with it. My Iwaki MD20 is maybe 400 gph?, so I dunno.

Another "live and learn" lesson.

Mike

 

[fishfreek]

If your only pushing 400GPH thru the overflow you only need one U tube. Its when you get above 600 or 700GPH that additional U tube will help.