We often receive calls from customers who have lost a lot of pool water and are not sure why. Some customers have accidentally left the filter on waste or backwash and the result is a lot of water pumped down the sewer fast. The water level ends up being low in the pool and sometimes the pump ends up starving for water damaging the pump. We have also seen holes in pool liners from the end of the vacuum pole if there is no vacuum head or leaf net attached. The open end of the aluminum pole can stab the liner fairly easily. Also check to make sure that your stainless steel pool ladder has the bumper stops properly installed and in good condition before they are installed for the season.