I am located on Long Island , NY and have a 20*40', 3.5'-8' deep vinyl lined inground pool with 4 wall returns and 2 deep end returns in the floor. The 4 wall returns and 2 deep floor returns are valved independently of each other. There is one 2" pvc pipe supplying the the 2 floor returns a separate 2" line supplies the wall returns. Using a 4.5 hp shop vac I was unable to get any air to blow up out of the floor returns. The shop vac cleared all other lines easily. Since there is no way to prevent water from flowing back into the floor returns even if I can blow them out , how is this handled. This is my first time closing this pool myself. It was previously closed by the pool builder without issue. I am thinking that the water level in the deep end return line will return to the same level as the pool water which is up to the bottom of the skimmers, about 1' down from the coping. I have a loop lock mesh cover. The shop vac displaced some water in the line since none is visible where the pipe comes up to the equipment and I poured a gallon of pool antifreeze down the pipe. I am concerned as to whether this is adequate. Thanks in advance for your help.

A Shop Vac is not designed to deliver a lot of pressure. I think that most are limited to a depth of about 5 feet. You can use a compressor to blow the line. While the air is coming out you plug the line to trap the air in the line.

Thanks for the info. I'm going to make up a quick connect to pvc adapter and use it with my air compressor. Then I'll just shut the valve on the line to hold the air in.
It didn't occur to me that the valves in the pool lines were air tight for the winter, but it makes sense that is what the builder did when they closed the pool last season.

Blow the system from the pump. Just go to HD and get a quick connect for your air hose. Screw it into one of the pump drain plug holes with a male/male 1/4" nipple.

Dang, if an air hose fitting fits those drain holes I've been doing it the hard way for........years!

Oh, I am very familiar with the fitting you are talking about, I must have a dozen of them sitting around my workshop. I just never realized that they might fit the threaded drain holes on the pump housing. I cant wait to check this out. It would be so nice to hook up the air hose to the pump, turn it on and walk around capping off the drains. Right now, I struggle with keeping the air in the lines while the wife races around the pool chasing the bubbles!

I just did the same thing but also added a 1/4" quarter-turn ball valve to I could shut it off and let the compressor recharge. It worked great.

Dude, thanks so much for this info. As soon as I read this I went and got a quick connect and it solved my 10' deep floor drain problem. I used a shop vac for the 2 skimmer/returns (which worked fine) but next season I will just rock all three with my compressor from the pump.

Go raibh maith agat.

By far that little air compressor fitting tip made closing so much easier. I made up my attachment and also added a small shut off valve to control the air flow right at the pump. Hooked everything up, blew out the return lines, repositioned the valves and blew out the main drain and I was done.....it has never been so easy.