Dumping the pool water -- how much?

[paula]

I have a 40 ft., 28,000 gal. gunite pool.
I just learned that the hardness of my pool water is 4000 ppm, so the water needs to be replaced.
My question is: do I need to drain all of the water out of the pool, or if not, than how much should I drain?
If I drain out the water, and leave it empty for a few hours while I replaster some spots, is there any danger that the pool will pop out of the ground?

[martyp]

depends I have emptyed mine 42,000 gallons but it would depend on your water table on where you live . Don't have that problem here