I installed a new Triton TR100. I added exactly what the installation instructions called for, 150# pea gravel and 450# of pool sand from our local pool distributor. The filter is doing a great job of filtering and no sand is getting into the pool until I turn off the pump for a minute or more. When I restart the pump, the filter blows about 1/2 pound of sand into the pool. I backwashed until the water is clear and then rinse until the clear inspection bubble window on the multiport looks clear too. Even after rinsing, I am getting the sand. Any ideas?? Thanks.