Over flow U-tube

[herzlos]

Does anyone else have the issue where small bubbles start to collect in the top part the Over Flow U-tube. Is there a way to fix this issue? I have primed it and got it so no air what so ever was in the tube. Shortly after one little bubble gets stuck. Then it snowballs. I haven't lost prime yet, But and worried that it will.

 

[veni vidi vici]

Could be to much flow going through it.Try slowing the flow a little bit.What pump and box are you using?

 

[herzlos]

I am using a Eshopps PF-300 Overflow Box, Max Flow Rate 300 gph. Using a Quiet One Pump Model 1200, GPH 296.

 

[t316]

Can you get a pic of the U tube in action?
If it's what I'm thinking you are talking about, why would the air bubbles matter? As long as you have syphon flow, air bubbles can't stop that.

 

[natclanwy]

The opposite is true there is not enough flow going through the tube. Too little flow allows the bubble to build up, increase the flow and the bubbles should get pushed all the way through the tube. What is the diameter of the U-tube if it is 1" it should actually flow close to 600gph even though they rate this box at 300gph. Also what is your head hieght on your return pump I am guessing you probably have about 5' of head and this will reduce that pump to about 150gph or less depending on the size of hose and how many elbows you used which is not enough flow to run this overflow.

 

[natclanwy]

Originally Posted by T316
http:///forum/post/2547691
Can you get a pic of the U tube in action?
If it's what I'm thinking you are talking about, why would the air bubbles matter? As long as you have syphon flow, air bubbles can't stop that.
When the bubbles accumulate at the top of the U-tube it acts almost like a valve slowy closing and restricting the flow and the pump will eventually push more water than is returning to the sump causing the display to overflow. I had this issue on my tank before I rebuilt my sump because pieces of chaeto would make it to my return pump and start restricting the flow causing the airbubbles to accumulate.

 

[veni vidi vici]

Originally Posted by natclanwy
http:///forum/post/2547693
The opposite is true there is not enough flow going through the tube. Too little flow allows the bubble to build up, increase the flow and the bubbles should get pushed all the way through the tube. What is the diameter of the U-tube if it is 1" it should actually flow close to 600gph even though they rate this box at 300gph. Also what is your head hieght on your return pump I am guessing you probably have about 5' of head and this will reduce that pump to about 150gph or less depending on the size of hose and how many elbows you used which is not enough flow to run this overflow.
Now that i think about it,you are correct .My return pump got clogged up and air built up in my U-tube.

 

[t316]

Originally Posted by natclanwy
http:///forum/post/2547708
When the bubbles accumulate at the top of the U-tube it acts almost like a valve slowy closing and restricting the flow and the pump will eventually push more water than is returning to the sump causing the display to overflow. I had this issue on my tank before I rebuilt my sump because pieces of chaeto would make it to my return pump and start restricting the flow causing the airbubbles to accumulate.
I had to think about it for a minute, but that makes good sense. Good diagnosis

 

[aquaknight]

Yea, you have a 300gph overflow and a 296gph pump without counting headloss. Definitely time to upgrade the pump!