Air Lock on Main Drain

JPMorgan · Oct 5, 2019

I am about to start my closing. I want to air lock the main drain. The main drain comes from the bottom of the pool to the skimmer (only one on my old pool) and the pool is about 9 feet deep. What size compressor will I need to air lock the main drain and how much pressure should I use? Also, if anyone has any instructions/tips on how to do this I would appreciate it. I don't want to do any damage.

Thanks.

ajw22 · Oct 6, 2019

See...

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Pool_Medic · Oct 7, 2019

You can also push a 4’ piece of foam rope into the hole and be done with it.

JPMorgan · Oct 7, 2019

Pool_Medic said:
You can also push a 4’ piece of foam rope into the hole and be done with it.

How do you get that foam rope down into the main drain line with the water pressure pushing it up? Any secrets?

Pool_Medic · Oct 7, 2019

Patience and good fingers, it will go, trust me.

1Sammy · Oct 8, 2019

Pool_Medic said:
Patience and good fingers, it will go, trust me.

Right on, just ask my fingers lol. What is funny is when you get all the way in and you take your fingers away to get the plug and the foam goes back over your head.

JPMorgan · Oct 8, 2019

Lol. I will give this a try, but if it gets tricky, I may just go ahead and blow out the line. I read this in one of the old posts mentioned above by ajw22:

"Typical 2" plumbing has a bursting pressure of 890 psi. So not really an issue for air pressure.
Glue joints, if done properly should be just as strong if not stronger than the pipe itself because of the double thickness of the pipe wall at the joint.
But all this is a bit moot because you only need 3.5 psi to clear a pipe 8 ft below water level. Bursting due to air pressure is a non-issue."

So..... looks like I shouldn't worry if I'm only using 3-4 lbs. of pressure to clear the line, right? I'm also assuming that it is not necessary to clear the entire line. If I get the water down 2-3 feet below the bottom of the skimmer there shouldn't be an issue with water freezing in that line right?

Pool_Medic · Oct 8, 2019

The key is holding the plug down with your pinky while using thumb and index to push the rope in. It’s poetry in motion ???