This spring, I changed the filter medium from DE to a cellulose fiber product called Fiber Clear. Water tests done by our local pool store over the last couple of months shows increasing phosphate levels since April from 100 ppb to 200 to 1000 to 750 to now 2000 ppb. The ideal range is < 100 ppb. The water analysis report provided by the pool store warns "Do not add PhosFree or Pool Perfect + PhosFree (which are the products sold by this particular chain store) to a filter using a cellulose fiber product, such as Fiber Clear." Apparently using Phosfree will gum up the filter grids.
What can be done (other than draining and replacing pool water as California is in a drought) to remove phosphates from the pool water if I have a filter using Fiber Clear? Is there any product or something else that can be done?
Thank you for your help!