The good news here is that almost all of the products we have researched and placed on our list have been designed that they will not harm the bottoms of pools that are made from materials such as tile, cement, or PVC. They achieve this by placing rubber bumpers along the bottom points. Some designs even use a series of suction cups to not only keep it in place but to also prevent it from moving around too much and running the risk of scuffing the bottom of your pool.