I fought this same battle last year and finally lost the battle. I resorted to using a clarifier which worked over night. But, I really do not want to add this to my pool. I have used the pool calculator at the pool school and kept my water over the mustard shock level for 3 days - still cloudy with no daily improvement noted. Only change is when I first started water had a greenish tint that is now more milky than green.
My levels at this moment:
As I said in the beginning - this same thing happened last year. I fought what I feared was mustard algae, as I had a powdery brown/tan substance on the steps and along seam lines on the bottom. I fought for several weeks last year with clorox till I feared I would ruin my liner - no improvement. I finally began to believe that this was dust and NC pine pollen, so I used a clarified - it cleared up over night - first treatment. So.....if the clarified worked by binding particles to make it easier to trap in the sand filter, then it stands to reason, my filter just is not doing the job. Am I right?
Do I need a new filter, should I replace the sand, or can I safely add DE to a sand filter. I have washed the sand twice this year already. Any thoughts?