plugging the lines - always get air bubbles

[run53]

Seems like I have the same issue every year. I blow the lines from the pump. Plugging the suction side (gizmos and main drain) all go well. Then the returns start blowing. I use the hayward threaded plugs with o-ring (and teflon tape) to plug the lines. The returns are below water. While the Mighty Vac is blowing, i always see tiny air bubbles after plugging each return but they go away as soon as I turn the blower off. This bothers me, but when I called the pool company that used to do the closings, they say not to worry about it as long as when I turn off the blower there are no air bubbles.

Should I trust their response? Like I said, this happens every year I close, and I never have any issues, but I'm wondering why those plugs do not seal air-tight. Anyone else see this?

 

[samt]

Seems like I have the same issue every year. I blow the lines from the pump. Plugging the suction side (gizmos and main drain) all go well. Then the returns start blowing. I use the hayward threaded plugs with o-ring (and teflon tape) to plug the lines. The returns are below water. While the Mighty Vac is blowing, i always see tiny air bubbles after plugging each return but they go away as soon as I turn the blower off. This bothers me, but when I called the pool company that used to do the closings, they say not to worry about it as long as when I turn off the blower there are no air bubbles.

Should I trust their response? Like I said, this happens every year I close, and I never have any issues, but I'm wondering why those plugs do not seal air-tight. Anyone else see this?

Those plugs work great in skimmer bottoms, but for the returns if you get the black expanded able plugs with the thumb nut, they work great for the returns. just be sure you get the right size.

I use to use the same as you with the same results, but once I switched to the rubber plugs it seals with no leaks.

 

[run53]

Those plugs work great in skimmer bottoms, but for the returns if you get the black expanded able plugs with the thumb nut, they work great for the returns. just be sure you get the right size.

I use to use the same as you with the same results, but once I switched to the rubber plugs it seals with no leaks.

I'm tending to agree. i may have to try them next year. I just thought the threaded plugs would be more secure. Even though I see a small amount of air bubbles get through every year I close, I've never had a problem and it doesn't appear much water, if any is getting back into my lines. I do put a couple of gallons of anti-freeze (from the equipment side) into the return lines just to be safe.

It just bothers me that I am unable to get an air-tight seal with those plugs. I'm wondering if my wall fittings have been compromised at all.