My cya levels have been so my pool is showing no chlorine after shocking. I have pumped out one foot and refilled multiple times and my cya is still 100ppm which the local pool store said is fine. Should I try to lower the cya to 30-50? Can cya be held up in the DE filter? It is an 18ft round with about 8000 gallons of water. I am not sure what to do at this point because I can’t get my chlorine levels up no matter what I do.