I have the SM1915SHG sand filter on my above ground pool. this year i added a salt chlorinator. I came home from work yesterday to find that my sand filter had sucked it self in (big dents all the way around it, as if the pump is to strong and sucked it in). I am using the same pump i have been using for about 4 years now (hayward 1.5hp that came with the pool). What would cause my sand filter to do this and what should i do to resolve the issue?