Antifreeze and main drain

burgerking089 · Oct 4, 2020

I’m closing my pool for the first time. From what I saw on the net, I should be pouring 1/2 gallon of RV anti-freeze into the skimmer line. I poured about a quarter gallon and it won’t go down any more. Is that normal. I did blow out all the water using an air compressor.

Also, main drain at the bottom was emptied using my compressor and was closed. Meaning the vertical part of the pipe is going to have air in them. But wouldn’t the pipe underneath the pool just fill with water? Does it not freeze because it’s below the frost line?

kimkats · Oct 6, 2020

I am not 100% sure so here is a bump to get this in front of more eyes.

Texas Splash · Oct 6, 2020

I suspect the pipes below the frost line will be fine. Your skimmer has two holes which makes me wonder if water flowed back to it from the main drain once you blew it out a bit. Can you confirm if your drain and skimmer are connected under there? Or does your main drain have a dedicated line to the equipment pad? You're still installing a Gizmo or placing cut-up pool noodles in the skimmer correct?

1Sammy · Oct 6, 2020

Good catch Texas, my thoughts exactly.

burgerking089 · Oct 6, 2020

The main line is separate from the skimmer line. And yes, just bought gizmos for both skimmers. Can the pipes have a weird pitch that’s causing this? In which case, rain water cannot get in there after it’s been blown out for the winter? In other words, I don’t need to worry?

Texas Splash · Oct 6, 2020

The antifreeze might just be stopping when you pour due to a turn in the line. Much like a P-trap effect perhaps since there's no pressure to push it through. But I'll tag @Catanzaro just to be sure.

1Sammy · Oct 7, 2020

The anti freeze will only go down until it reaches a high spot in your piping that is at the level of the bottom of the skimmer.

RebelBob · Oct 7, 2020

My two cents re. Main drain. Think about what happens if you plug a straw, even one with a 90 degree bend at the end, with your finger and then put it into a glass of water. Water does not go into the straw. Release your finger and water comes in. I just did it myself in the kitchen!

Catanzaro · Oct 9, 2020

One of the things I have learned with the main drain is that antifreeze is usually not needed, as it will mix with the water. You are too far down to worry about anything. The air will actually compress in the cold weather and expand in the warm weather. One other thing I have learned is that the shut off valve is not 100% air tight. Even after I replaced the new one, it is not 100% air tight as I can still hear air hissing on the way back. What I do is plug the pump basket housing with a winter plug, and the air hissing stops, then close the skimmer towards the main drain, side as well to try to prevent air from coming in.

At least the main drain has room for expansion if the air is lost during the closing season. I would be more concerned with soil moving as all land shifts over time, and causing movement in plumbing, which could eventually cause problems. Broken pipes happen, not on a very small scale.