Hi everyone. For years I have used a blower to blow out the lines on our vinyl liner inground pool at closing. I have not typically lowered the water below the returns and wall vac inlet - only about an inch above the returns.
I tag teamed with my husband to get it done: I run the blower at the filter deck, he holds a threaded wall plug wrapped with teflon tape and fights the thrashing water to get the plug screwed on.

This year the tape came off all three plugs and he said not to bother with it. I am a little leery, as the three lines were replaced 4 years ago ($3K) and I don't want to do that again any time soon (the originals lasted 23 years).

First off, with a vinyl liner IG is it safe to lower the water below the lines (which are at least 22" below the water line) so that we can see when the lines are empty and then plug them? Is it safe to NOT use teflon on the threads of the plugs?

I don't like feeling like a harpy - he feels bad that I don't trust him, but I want to know that the lines will be safe, that we won't bicker and I won't have to spend another $3K or more to replace the replaced lines.

We still haven't had a cold enough spell in the lower Hudson Valley of NY so I know I still have a little more time - but not a lot!

Thanks everyone for your help!