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The simplest way to change the water and the industry standard is to replace the water with water proof bricks ,bricks must be sealed, Thompsons is good, 2" disposable brush. The bricks will displace the water once the pool is full of bricks start refilling the pool and removing the bricks at the same time kind of a balancing act. You must realize you will only get at best 85% of water out. but that would be enough to get you stabilizer level down. In reality "your friend needs to find another pool supply store to deal with and learn how to take care of a pool correctly.