Hello i have an inground pool 16x32. I m currently using a hayward cartridge filter. The problem im having is i keep getting brown sandy substance coming out the pool jets and settling on bottom of floor underneath the pool jet returns. I always hose off dirt from cartridge. Too see if it was actually the cartridge i ran the pump without it in it. Ans i didnt notice any dirt at bottom of pool. This is driving me nuts trying to figure out what issue is. Please help! My ph is 7.6 only thing low is alkalinity level.