I have a Hayward Swim Clear filter and a Hayward 400k BTU heater. The heater has a safety feature where it won’t heat the water unless sufficient flow is in the system. For me, that’s 2250 rpm. Today the heater wouldn’t come on. This happened before and I called Hayward and they said my filter was plugged so the pump needed to be turned up. Sure enough the pressure was high. I turned it to 2650 today and it came on. A few hours later I cleaned the filters and found excessive iron buildup on the pleats. See photo. I put in brand new cartridges. I cleaned the old ones as best I could with a filter flosser but they definitely did not come clean . I set them to soak in TSP solution but I really don’t think that will do anything. Any ideas on how to get rid of the iron? Ascorbic acid? What concentration? These filters are about 1-½ years old and should last longer than that, no?