Losing antifreeze from return line - any ideas?

[clearpools]

Hi all,

First time pool owner, first year winterizing. TFP has been a great help with everything.

I'm confident the skimmer & main drain are winterized well, but the return line is making me nervous.

When I opened up this spring, I noticed owners (or pool store) drained below return line, and left it uncapped.
I didn't drain below return, & instead used shop vac to blow out from equipment pad & used one of the threaded plugs with an O-ring to cap it while it's bubbling.

On capping, it didn't look like it was leaking any air. To be "safe", I bought some RV antifreeze & filled the return line, again from the equipment pad.


The return line from the filter has some clear pipe where I can see the antifreeze -- see photos (inside filter & outside)

(Note: the 2 black pipes sticking out of the ground on the left side of this photo are just 'open' - I have no idea what they are for)


I figured "oh good, the pipe is filled with antifreeze"". Took about 1.5 jugs to fill it to this point.
Few days later, I check, the antifreeze is gone from the pipe.

I added some more, it took half a jug to get to the point where the visible pipe is filled w/ antifreeze.
Few days later, the same thing - antifreeze gone.

Same story, added a half jug, but this time I capped the filter drain plug & closed filter inlet jandy valve after.
Once again it is a few days later & antifreeze is gone from the visible pipe...


Any thoughts on a path forward? I'm not sure that I trust my winterization of the return line... Nor do I understand why I'm 'losing antifreeze' -- leak in the pipe, leak in the return cap, or something else?

Maybe I should just use my cover pump to drain the water below return lines & call it a day.


Thanks everyone. I appreciate any help, and If you have any questions let me know.

 

[1Sammy]

Hopefully it is the screw in plug with the O ring. I always wrap the threads with teflon tape just to be safe. Should be easy enough to check. You can add pressure to see if any antifreeze is sneaking out. For a drop in level that much that fast it would require that screw in plug to be pretty loose, sorry. My "guess" is that water got in the uncapped return and you know what...

 

[clearpools]

Thanks Sammy.

Today I uncapped the filter drain plug so I could hook my shop vac up to the return line.

I tested adding some pressure while watching the return plug to see if i could catch it leaking. No obvious signs of leakage and I did get 'blow back' when i let off the shop vac.

I tested adding suction and saw antifreeze come up into the visible pipe in under a second. Looked undiluted, which was a confidence boost. Maybe there's a leak somewhere between the visible pipe and where the antifreeze has settled.

I'll probably continue draining the pool below the return, and try adding suction in a couple days to try to determine if antifreeze is still leaking.

 

[1Sammy]

Not following ya on the suction thing. With out a pressure gauge in the line and a 100% seal shut off it proves nothing. I can only say, if you fill a pipe with antifreeze and it drops by the half gallons, you have an escape some place.