I just finished my second perfect pool season on the BBB method. Towards the end of last season I switched over to a DE filter (Hayward Perflex EC50 DE Filter) and didn't notice anything unusual at closing time when I took everything apart. This year after a full season there was a considerable amount of gray sludge at the bottom of my filter. Is this normal and I should expect that at the end of a season or did I do something wrong? According to my understanding of the instructions I'm not supposed to backwash this filter at all, just bump it after I vacuum the pool each time which I did.
Am I missing something?