Closing new pool - Main Drain Issue

[somersguy]

Hi,
I just bought a new house with an inground gunite pool and I’m trying to close it. This is the first pool I’ve had that has a main drain, so I’m running into some issues. I blew out the 2 skimmers and the 4 returns, along with a separate return line that the zodiac vacuum used, but I can’t get the main drains to blow out. In addition, even though I completely separated the return and suction lines, I get water coming out of the return near the valve when I’m trying to blowout the main drains on the suction side. Shouldn’t these be totally separate? I’ve attached some pics. Any help would be appreciated. Thanks.

 

[Texas Splash]

It's often very difficult to blow-out a MD line completely. But simply by introducing the air as best as you can helps to create a void of air and allow for expansion, even though the line is fairly protected below the frost line. Can you confirm what you are using to clear the lines? Shop-vac, Cyclone, etc?

As for the residual water from one return, it must be moisture trapped between the skimmers or something. Maybe some of it pulling-up from the drain line? Water can't cross-over from pressure to suction or vise-versa. Maybe just a coincidence. But post back and let us know if you have any other concerns. Others who close like you might more to add.