Suction side air-leak issue on inground pool

[fletcher_101]

I have a suction-side airleak that I can't find. I know it's not the joint between my basket and my first valve (I can isolate those sections and pull from my spa and it's okay) and I've tried all the tricks to find it, including checking/replacing all of the gaskets in the valves. What's confusing is that the pump will hold it's prime overnight. My pad is perfectly dry and I sealed all of the accessible joints with silicon just in case, but I'm still getting air.

The big question: why is my pump holding it's prime when I know for sure there is an air leak? Does that indicate if perhaps the leak is underground, or maybe it's a crack in a pipe as oppossed to a break in a joint?

Thanks

 

[JohnT]

What is happening that tells you it's an air leak? Bubbles in the returns or in the basket? Can you post details about your pool and equipment?

 

[fletcher_101]

Gunite inground with a spa. I can control where the water draws prior to it entering my pump basket. When I draw from the pool (from the skimmers and the drain together or separately), there are lots of air bubbles coming out of my jets and I can see air moving through the pump basket (looks like a tornado in there). When I draw from my spa, all the air goes away.

I have no doubt that air is coming up from the pool piping. What's puzzling me is that I never lose the prime when the pump is off. If I've been drawing from the pool, there is more air in the basket after I shut it down, but the water still pretty much covers the 2" inlet pipe. If I open the basket, what's there will drain back through the piping like it should.

Strange magic.

 

[duraleigh]

What's puzzling me is that I never lose the prime when the pump is off.

When the pump is on, the negative pressure on the suction side is allowing air to leak in somewhere.......however, when the pump is off. the negative pressure becomes positive pressure and the leak is sealed.

It sounds like the O-ring around the pump basket lid but I'm sure you checked that. I suppose that type of leak could also be in a drain plug at the bottom of the pump strainer basket but that doesn't seem as likely.

Wherever it is, I would suspect a rubber gasket that would reseal when positive pressure is applied (i.e. the pump shuts off)

 

[JohnT]

When I draw from the pool (from the skimmers and the drain together or separately), there are lots of air bubbles coming out of my jets and I can see air moving through the pump basket (looks like a tornado in there). When I draw from my spa, all the air goes away.

I'd guess Dave is right, but here are some other thoughts/questions/ideas to help with the troubleshooting process:

1.5" or 2" plumbing? How big is the pump? Any changes to the equipment or plumbing before this happened?

When you draw from the spa, does the return water also go to the spa or is it going to the pool?

You might want to check that your skimmer weirs move freely and aren't making any noise when drawing from the pool. You could get bubbles on the drain alone from a lack of water flow, not a leak. On my pool, I get bubbles if I run drain only, but it's because the drain can't supply water quickly enough to keep up with the pump.

 

[fletcher_101]

The gasket makes sense. I opened a valve yesterday to check the gaskets and after I closed it, the pump was no longer holding it's prime at all. I'll replace all the gaskets and use silicon around the inner edge and see what that does. Thanks.