I just just had an 18 X 36 IG installed about a week ago. It has a hayward 1 1/2 pump and 300 lbs sand filter. After I backwash and rinse, I get this large dust cloud out of the returns for 30 or 40 seconds. The pool looks so nice cleaned but I hate to backwash because it appears to put more sediment back in the pool. Do I have a problem with this filter? Any help would be appreciated.