I am closing the pool on my own this year and have some questions about closing the in-floor cleaner. In the past, my pool guy has removed the heads from the top 2 steps and plugged them with rubber plugs. However, when I blow out the ports, they still have water in them. I am using a shopvac from the valve side. Lots of water blows out of the heads on the step but seems to keep going forever. I suspect that the heads on the 3rd step is also connected to this discharge line. When I stop blowing the line out, it fills back up to about 1ft below the step. Is this normal? Do you use anti-freeze in the lines before plugging (both valve and head sides)? Thanks for any help!