It depends on if you mean damage to the liner, the bottom or the walls. The liners go bad and shrink if not kept wet and evidentally this can happen very quickly. The walls should be held in place with braces and a concrete footer if it was installed properly and the weight of the concrete apron (sidewalk around pool should keep walls in place so these should normally be safe. The pool bottom if it is not too old is probably a mix of vermiculite adn cement from 2-4inches thick and this can be damaged if your water table is high in your area. If this is true them hopefully who ever installed pool should have put in a sump or french drains ect..to help keep water from coming up under pool and pushing the bottom up. You have to remember that at some point your pool didnt have water in it. ie during construction.
Yes.
Closed
Vacuum the pool. If you have to drain it, only drain it half way. Floating pools are a disaster.
You don't drain an inground swimming pool, unless you are trained to do so. Doing it alone or even with assistance is extremely dangerous. Save yourself some trouble and go contact a local and trained swimming pool cleaning service.
sounds like there is ground water getting in there somehow
Why would you drain your pool just becasue the water is hot? Never drain your inground pool unless you have first cut holes in the bottom of the pool to keep it from floating. If the water table in your area is high enough, your inground pool could "float" out of the ground, effectively ruining your pool.
another clog, further down the drain pipe. You need a drain snake.
The skimmer is the healthiest method for removing water from a pool for filtration at all times
Depends on your setup. Do you have a working bottom drain and a side skimmer basket? I only have the side skimmer basket, so once the level goes below the skimmer the pump will run dry. I have to attach a vacuum line to my skimmer basket so that the vacuum head sits at the bottom of the pool then I can backwash as much water out as I want. You should note that I have read draining all the water from an inground pool will damage the pool as the walls and liner rely on the water pressure to keep shape.
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Nope. Sorry, but the only way is to drain the oil, find the reason for the water in the oil,repair the problem and check for bearing damage.
No. You just drain out enough water to close up the skimmers/plumbing, but the pool remains mostly full.