First time Closing Pool Help

[jasongreenberg]

This will be my first time closing my in-ground pool and I am having one line that I'm not able to blow out with my shop vac.
This line is one of the two pipes that are at the bottom of my skimmer (there is only one skimmer).

I have drained the pool below the returns and I blew out all return lines and the suction line that goes from the skimmer to my pump.

The only line left is the other line that exists at the bottom of my skimmer. I'm not even 100% sure what this line does/where it goes, I am guessing that it goes to the main drain at the bottom of the pool. If I try to blow it, I don't see any bubbles coming from the main drain. If I try to vacuum this line, water just keeps coming out and it refills itself always to the same level. There was a gizmo in this hole when I opened the pool and there was antifreeze in the gizmo, so maybe I don't need to blow it, just pour antifreeze in it? The other line going to the pump from the bottom of the skimmer was plugged when I opened the pool.

I should also mention that I don't see anywhere in my pool shed where the main drain line is fed back to the pump or anywhere for that matter. I have disconnected all lines I see in the shed and have figured out where each one goes, but nothing going to/from the main drain at the bottom of the pool.

So just need to figure out if I just pour antifreeze into the gizmo that's plugged into this mystery line and be done? Or should I do any more investigating? I am in Canada so need to be ready for very cold winters.

Thanks for any help!

 

[jblizzle]

The mystery line likely has to go to your floor drain. What are you trying to blow air into it with? It may not be powerful enough to push all the water down and out of the floor.

 

[jasongreenberg]

Yes, I suspect the line is the floor drain as well. I am using a 1.25 HP Wet/Dry Vac to blow the pipes and it's done a great job with all lines other than this drain line. The previous pool owners left this wet/dry vac in the pool shed, so it seems they have been using this to blow the pipes in the past. If I remember correctly, this line wasn't plugged when I opened the pool, it had a home made gizmo like tubing device which was screwed into this line directly in the skimmer with antifreeze in the gizmo and some foam. Not sure if that is enough because I suspect that the water in the pipe can still freeze, not sure if the antifreeze would mix with the water throughout the entire line or if it would just sit on top of the water in the gizmo?

From what I read, the water should be below the frost line. How do I know where the frost line would be?

 

[jasongreenberg]

Ok, I'm now sure that this "mystery line" is going to my main drain and is used to keep the skimmer water level up even if the pool water level goes below the skimmer. So I've plugged the other skimmer port (after blowing it) which is the suction line that feeds the pump and I have put in my home made threaded gizmo in this drain line to keep the water from overfilling back into the skimmer. From my I'm finding online, I'm thinking the best way to move forward would be to put a foam rope into this homemade gizmo and down the pipe mixed with a bit of antifreeze. Just wondering if I need to plug the end of this gizmo or leave it open? It was unplugged when I opened the pool at the beginning of the season. Is there a reason to close it?

How does this all sound? Will this be sufficient? I have attached a photo to help illustrate the setup.

Lastly, I am starting to think that my main drain line isn't really a drain, it's just a line feeding this second hole in my skimmer to keep the water level in my skimmer up. I don't see that this line makes it to my pump/filter etc. Seems strange no?