Bubbles in the Pump and Returns. Am I guessing right?

[AndrewWoo]

Started getting bubbles in the return lines a couple weeks ago. Trying to figure out where it might be coming from. It's definitely on the suction side, since there are bubbles in the pump basket.

The bubbles enter my pump basket when the main drain only is on. When I add another intake (skimmer, for example), the bubbles go away. The bubbles don't happen on any other combination - only when it's main drain only.

So my guess it that it has to be the main drain. Is that assumption right? I also used a trick a friend told me about and burnt some incense sticks near the pump. Moving the smoke around all the fittings and valves to see if the leak would show itself by sucking in the smoke, but no luck. At this point I have to guess it's on the main drain and below the surface.

So before I start digging, am I on the right track? My thought was just to dig below the ground until I hit the first 90 that goes towards the pool, then check that fitting for leaks. Anything beyond that seems like I should hire someone.

 

[COBrien]

My guess would be that your leak is above ground somewhere.

What type of valve are you using to switch between skimmer and main drain, and how old is it?

Most of these pool valves can be serviced (i.e., rebuilt) quite easily. It could be something as simple as a dried-out or cracked seal inside the valve.

 

[AndrewWoo]

My guess would be that your leak is above ground somewhere.

What type of valve are you using to switch between skimmer and main drain, and how old is it?

Most of these pool valves can be serviced (i.e., rebuilt) quite easily. It could be something as simple as a dried-out or cracked seal inside the valve.

Thanks for responding! I have Pentair valves. Skimmer is on it's own (on/off), and the main drain and vacuum line share a valve. The valves are 2.5 years old, when I had a new pump put in. I can open them up and lube the seals tomorrow, or see if I need to replace one. Seems awfully soon, but I haven't done anything to them since they were installed.

 

[mas985]

I would first inspect and lube the pump lid and drain plug gaskets.

When you isolate the MD, it can decrease the pressure in the pump basket making it more likely to leak air.

 

[AndrewWoo]

Worked well. Got 90% of the bubbles out. Thanks!