I always have more then a few areas where there is dirt on the bottom of my pool. I touch it and it feels grainy like sand. I dont know if it is dead algae or dirt/sand but like i said it feels grainy when i touch it. I bought the expensive sand/dirt bag to attach to my vacuum but still the same results. I cant even say for sure that the sand/dirt bag even helped. How do i keep it all the way clean.