Just closed our pool after the first summer, I've kept the pool very clean all summer, when I closed it I noticed that I lost a lot of sand during backwash. This has been consistent all summer, in the back of my mind I thought perhaps it was because the filter simply didn't need back washing - not so sure now.
Installation for the filter went fine - didn't notice anything wrong inside the filter, no parts broken off inside, added sand slowly with the sand guide.
BUT, one time during the first couple of weeks of my newbi-ness I turned the valve handle while the pump was still going. Could this be enough to wreck the multi-port gasket and allow sand to get through.
Or could it be that the filter medium simply doesn't require backwash? I recall reading somewhere that unless the sand requires backwash you can blow sand out of the filter (not sure if I'm grasping at straws now).