U-Tube for my overflow keeps accumulating bubbles.

Hi guys. Just wondering if anyone has any ideas on how to correct this problem. I have an Eshopps PF-NANO overflow that uses a 1" U-tube for the siphon. I've noticed that overtime it collects little bubbles at the top of the U-Tube and eventually it becomes a big bubble that already takes up half the top of the u-tube. I just leave the airline tubing in the U-tube and I constantly have to blow air into the u-tube to kill the siphon, and restart it to get rid of the bubbles. Any ideas guys? Thanks!

 

It needs more flow, do you have a ball valve on your return?

 

OK if you are leaving the airline tubing in the "u-tube" - you need to take it out ASAP.

The most important things to remember with these overflows IME:

1: Start with a perfect siphon - keep a perfect siphon. If you have ANY air in the siphon to start - redo it. Takes some tinkering but once you get it you will not have to redo it constantly as it sounds you are doing now.

2: Adequate flow. If you are not flowing enough water, the small bubbles accumulate instead of being forced out.

What flow rate are you running on that overflow? Any idea?

 

Sounds like Ocean Man is right. I see bubbles go in mine but the flow is so great that it sucks them through before they have a chance to settle.

 

Yes I have a ball valve on the return. But how would the ball valve on the return affect the flow rate of the overflow? I don't understand.

Yes, I would always take the airline tubing out. But when I noticed that it would always accumulate bubbles over time, I just started leaving it in so that I could stop and restart the siphon right away.

Sometimes I get the siphon really good. But there are tiny micro bubbles that are stuck to the tube in different areas(not just the top). And I guess overtime, they move up to the top.

The PF-Nano is rated for 200gph. Any ideas on how to up the flow to get the water moving faster? Thanks again guys.

 

If you had a ball valve I was gonna say open it up some to let more flow into your tank. You can't raise the flow out if the flow in doesn't increase as well. I have an eschopps overflow as well, when setting mine up I noticed bubbles accumulating and opened my ball valve which increased the flow into my tank, which then increased the flow out. I.E. more flow through the "u" tube.

 

Ahh i see. Does this have something to do with more water in the display tank, therefore more pressure going into the skimmer box? I will give it a shot. I also realized that lowering the skimmer box also increases the flow slightly. But the bad thing about that is that if the pump is turned off, my overflow will probably continue to take in too much water, causing my sump/fuge to overflow. its only a 5.5 gallon fuge for a 20 gallon tank. Thanks guys. Any other ideas to increase flow?

 

only way you you can increase flow is with your return, they HAVE to be in equilibrium. if not either the sump runs dry and DT overflows or sump overflows and dt drops too low.

 

aqua lifter on a timer will fix it if no one said it already

 

thats true...but you gotta buy it and plug it in and replace the valve every year...in reality its a very cheap solution and provides a very good amout of piece of mind.