Very smart advice to just remove it and resurface as you said, very VERY smart to do now when the pool is empty and liner's being swapped out. The liner guy that I'm now probably not going to go with simply because some of his 'facts' were incorrect (a big tipoff that something's not right--he should certainly know the mil/gauge of the liner he's pushing as well as which mil is on the sides and which on the bottom) said there's probably vermiculite behind the liner, not concrete, can this substance be resurfaced? I always thought it was concrete because it's so hard. My only experience with vermiculite is that it was the tiny goldish *soft and loose* stuff (like confetti) that was in the attic of my old house in Mpls. (before I moved here to Alabama).

I'm so glad you hopped into this thread. I will most certainly have that drain cap filled in/however it's done, assuming it's doable. Then I can dismiss any potential problems down the road/getting sucked into it and becoming part of the Alabama underground landscape. Umm, but how is it filled in since there's a hollow pipe below it? Sort of like when I go to caulk something when the crack is too big you have to put something in there or the caulk would just go down down down?