Air Leak Source?


Active member
May 21, 2016
Harford County, MD
Opening this season has been a nightmare compared the the prior three. A myriad of issues including:
  • Cracked air relief valve, followed by a second one
  • Broken divider in my multiport detailed here. Replaced gasket for now.
  • Pool leak supported by bucket test
  • Leaking DE filter clamp, 2 attempts so far, but still leaking
But the most confusing issue is an air leak that mostly appears after the pump is off. My pump does not run from morning to early afternoon and each time it starts at 3PM, there are bubbles shooting out of one of my return lines and a large bubble in the pump basket. Typically I can open the air relief valve to eliminate most of the bubbles, but even after that I will still get some small bubbles every 5-10 seconds or so. They coincide with "wsshh" sounds that I think is air entering the system. When I'm standing by the pump I hear it come in through one of my suction lines and works its way through and out the return line.

Things I'm confident are NOT causing the issue:
  • Pump basket lidthr
  • Pump basket drain plugs
  • Pump inlet
  • Pump outlet
  • Skimmer weirs
  • Water level
On higher pump speeds the bubbles seem to dissipate after about 5-10 minutes. On slower speeds I get a continuous quarter size bubble just beneath the pump lid.

Could any of the other problems I mentioned be contributing to this?

Appreciate any thoughts.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
It's possible you may have (or had) more than one issue happening at the same time which only complicated things. You may already know that VSPs are notorious for showing a little bit of bubbles in the pump pot when left on low rpms for a while, so ruining at a higher rpm is fairly common to blow-out those pesky bubbles. A dirty filter can restrict flow which also can lead to a small gap under the pump pot clear lid. What about 3-way valves before the pump? Those can develop an air leak as well. Whenever there is a break in the pressure side like an air relief valve or filter band clamp, it may be too small to notice when running, but once off air gets sucked-in to the plumbing. You mentioned the pump inlet/outlet, so I'm not sure if that means you also reached inside to feel the impeller area for any obstructions or something that may wrapped around it? Then you mention the suspected pool leak. If that's on the suction side, it might be pulling a small amount of air in as well. If you have more than one suction source (i.e.skimmer, main drain, suction line vacuum), then any of those could be suspect.

I would definitely be more concerned with the potential leak at this point since that can impact your overall pool support and cause changes in chemistry. If the air bubbles you are seeing aren't significant or result in a loss of pump prime, I might be inclined to say don't get too worked-up about it for now. Just keep an eye on things to make sure it doesn't get worse. I was chasing the same type of thing for a couple years than finally backed-off. I was going nuts. :crazy: No changes and everything is fine.