Main drain bubbles after air lock closing??

[noelc]

Just wrapped up closing my pool. Everything looked good for a while but....

As I went to go double check I noticed the main drain is bubbling every few seconds. I verified I have this air locked.

At the moment I do have 10 PSI of air pressure making sure everything holds. However I would not expect that to get past the Jandy valve for the main drain.

Should I be concerned or is this normal for a little while.
Does this mean I might have a leak in the piping in that main drain line?

Thanks!

 

[Catanzaro]

Just wrapped up closing my pool. Everything looked good for a while but....

As I went to go double check I noticed the main drain is bubbling every few seconds.

You are losing air. Air is being removed from the "lock" and water is either coming back into the pipe, or air is escaping at the bottom of the pool (one or the other), my best guess.

I verified I have this air locked.

Please explain what you mean by verified? Does this mean the shut off valve is in the "closed" position?

At the moment I do have 10 PSI of air pressure making sure everything holds. However I would not expect that to get past the Jandy valve for the main drain.

Please explain in detail what "having 10 PSI of air pressure making sure everything holds" means? Is this the amount of pressure you used on the air compressor?

Should I be concerned or is this normal for a little while.

I do not know if this is normal, but saw this once in my friends pool for a few seconds, but then completely stopped and we were out there for a while as I checked frequently. With my pool, there are no bubbles. Once the shut off valve is closed, and air compressor off, the bubbling effect almost stops immediately. There is some residual small bubbles through the water, but within a few seconds they stop.

Does this mean I might have a leak in the piping in that main drain line?

Anything is possible, but I am betting on air is leaking at the valve. As you slowly lose air, bubbles occur.

 

[Pool_Medic]

Trying to air lock a main drain isn’t necessary. There is a reason no pool company ever does it and no damage results.

 

[noelc]

I did check the valves and they are in the off position. I have two. One main drain and another for solar recirc. I did check closely and I am hearing air loss in the solar recirc valve.

The 10 psi is a pressure test I am doing. I had a system leak earlier so figured this was a good time to test. I blew in air into the system and the air filter pressure gauge is at 10 psi.

I am thinking the additional air pressure is causing the leak. I may try to reblow the main drain and relock...without the pressure test.

Thoughts on anything else else I can do?

 

[Catanzaro]

Thoughts on anything else else I can do?

Looks like you have it down pat. You can clear the main drain line again and close the valve, then call it a day.

 

[JamesW]

The main drain line is clear. Most likely, the bubbles are from the 10 psi of air in the system leaking past the closed valve indicating that the valve is not seating 100%.

People routinely blow out the main drain and air lock it to winterize the line.

Now for the main drain. Re-position your valves to blow air back through the main drain. When you see the massive plume of air rise up, allow another 20 seconds and then close off a positively sealing valve (like a Jandy valve) on the main drain line, to hold the water back with a column of air.
How to Blow Out Pool Lines for Winter | InTheSwim Pool Blog

 

[noelc]

Thanks everyone. I opened the valve in question and it blew out a big burst of bubbles and I quickly re-closed. PSI dropped and it looks like the airlock is holding. No more bubbles. Looks like it was the 10PSI getting through the valve and pushing some additional air out.