On 5/28 we vacuumed, and after cleaning the basket at the pump, the dh forgot to turn the filter from closed to filter. It ran on closed for a couple of minutes before he realized it. Everything seemed ok until 4 days later when I noticed a possible leak and water near the pump and filter. He will be home this a.m. and we are going to check for a leak then. Wondering if we damaged the filter at that time and how often do you change the sand in a filter? Thank you!