Disclaimer - this is my experience only. I am not a pool expert, just an avid DIYer, so I may not know what the heck I'm talking about. Your mileage may vary, proceed at your own risk, etc. (i.e. don't come crying to me or try to sue me if anything goes wrong).

I've had my pool drained for my DIY remodeling project for about 2.5 months now. My drain has a hydrostatic relief pipe in it, but when I drained the pool I found that it had never been capped, so I'm guessing it must be clogged up (otherwise I suppose the water would have drained out).

I thought about drilling a couple of holes in the deepest part to provide hydrostatic relief, but opted against it. One, I was concerned about being able to patch them sufficiently. But also, I talked to a couple of people in my neighborhood who had pools put in recently, and they said they never hit water during the excavation (and one of them even has a deep end, vs. our "party pool" which is on 5' deep). So based on that, I'm assuming the water table isn't very high in our area.

Just to be safe though, on 3 different occasions during the last few months I have partially filled the pool when we have had heavy rain. I usually just put about 18-24" of water in it, to provide some extra weight without wasting too much water. Then I pump it out after the rains stop (usually waiting a day for the ground to dry out some).

I also think the stories of pool shells experiencing extreme "pops" are rare and/or exagerated. But I don't think it's that uncommon to experience some slight shifting if the pool is empty for an extended period of time. I wouldn't be too surprised if I fill up my pool and the water line at one end is now an inch or two higher than the other. That happened to a guy I work with just a few months after his pool was built (and it was full of water), but he just learned to live with the pool not being perfectly level, and after 20 years it hasn't got any worse.

We just finished our remodel yesterday (pavers, coping, tile and pebble) and the pool stayed empty for 1 month. We had no issues with the pool shifting or popping out. After they drained the pool, they unscrewed a plug at the bottom of the main drain and also the spa drain and watched if ground water came up. Since it was dry, they did not have to install a pump while they worked.

Our contractor told us a story of a pool remodel that they did and the homeowner was trying to be helpful and drained the pool himself. Well, he did not know about the plugs in his drains and left them in . This was during rainy season (August in Florida)so the water table was very high and his pool popped out of the ground about 3 inches overnight.

Lesson learned, leave it to the professionals. If you have a good contractor, the water table should be the first thing he checks before starting any work.

Looked at the pool today after tile/coping were removed and draining completed, and sure enough, they had drilled several holes in it. Some of them are still draining after 24 hrs, and so are some of the cracks!! We knew the cracks were leaking, though, so I guess that makes sense.