16x32 19K gallon IG with a vinyl liner. Liner replaced ~5 years ago. Galvanized knee walls had some rust. They pretty much just put foam sheeting up right over the rust from what I know. Last year I noted what seemed to be rust blossoming behind the vinyl liner directly below the skimmer (skimmer, outlet and inlet were all replaced then too...plumbing wasn't, but it is all like flexible heavy duty radiator hose, which they said was the best thing to have up here). I called the outfit that put it in, but they were too busy closing pools to send someone out. So I just checked the screws and snugged them up a little, thinking perhaps that the cold weather had some impact. No significant water loss noted by the way.
This year I didn't notice any significant water loss, excepting during one brutally hot week in July. My filter leaks a bit too at the clamp so I didn't think anything of it. Just notices lots more rust blooms, further to the left of the skimmer (standing above it. Not just two, but more like a half dozen (two original ones don't seem to have returned and there aren't any just below the skimmer, for what that is worth.. At this point I need to fix it if possible and close the pool.
In an aside, my test strips say my water is too hard. I looked and it seems like the only cure is to do a partial water change. I have a lot of iron in my well water, but I usually condition the water that I put into the pool. I also pump rain water off the cover into the pool to change it up a bit.
My pool just has grass around it and a few patio blocks, so it is possible that the wall is getting wet from behind and rusting from there. However, it is also possible that the skimmer it leaking and that chlorinated water is traveling laterally from the skimmer to attack the wall. However, If that is true it should hit the foam...but it may be that the interface between the foam and the skimmer wasn't constructed to keep the water off the walls like that.
I was thinking about trying to change the skimmer gasket (last year I tried the food coloring leak test but really didn't find anything), but it seems that isn't the way to go. So, based on what I have seen recommended should I drop the water level below the skimmer, silicone the interface between the gasket and the face plate and the skimmer box, then leave the water level down below this skimmer for the winter? I could even take it down 18-24 inches because of the hardness and then fill it back up a bit, putting rain water under the cover to do the rest.
Note that I always put a plastic bottle in the skimmer in the winter and there is no evident damage to it.
Thanks in advance for the help!