Closing an AG Intex Pool

[nrbarnard]

I read the thread about closing an AG Pool. Had a couple questions.

Is there a certain air temperature that I should wait for before closing? For example, should I wait longer even tho I am likely done swimming or is it better to close earlier?

I read pools are drained below the intakes, but then plugged. Why plug them if you are intentionally draining below them? Why not just plug the intakes/outtake, remove the plumbing and keep the water full? I ask this because the village water is loaded with iron. Rather not load it up with more this next season.

EDIT: Also wanted to ask if there are concerns about the water freezing?