I haven't had to post on here in a while because this forum has taught me so much and my pool is crystal clear! This post is actually for a friend of mine that I'm helping out. Their CYA is above 100 so I told them that there only option is to do a partial water replacement and then SLAM. My question is, I would like them to replace half the water in the pool but they have a liner pool with two sun shelves, how much water can they remove without affecting the liner on the sun shelves. Should they do it in phases or drain half the pool all at once? Here are some pics of their pool for your reference. As always, thanks for your help!