I recently had my pool resurfaced using Diamond Brite as my finish. My Pool was filled just over one week ago with water hauled in from the local aquafer..(all $780 worth.) I added two gal of liquid shock while filling. And added two additional gallons a few days later. About three days later,I installed my new DE filer system which included a Pentair inline chlorinator the uses h 3" trichlor pucks. Which I seen no harm in using initially because my new water should not contain any CYA. I filled my chlorinator wih 5 pucks ( it holds 11, I believe) an set the feed on 3 which is about half strength. After circulating for about 4 days. I took readings with my TF 100. results: Chlorine 0, PH >8.2, Ca hardness 325, Total Alk 290, CYA ???? Dot never became invisible. Later that evening, I added 2 gal of liquid shock to see if it would hold over night. The next morning my readings were: free chlor 5.5, combined chlor0.5, PH still > 8, total alk still near 290, CYA the dot still never went away. Reading two days later which was this morning: No chlorine present, PH >8, Total Alk > 200, CYA dot still visible as tube ran over???????.
OK, I'm not sure if the water from the aquafer was extremely alkaline to begin with or if the Diamond Brite curing process adds to the issue. Regardless, I figure I can fix that problem with acid, aeration and time. But what perplexes me is the CYA level. Am I getting false CYA readings due to other issues with new well water? By the way, the water is crystal clear and has been since day one.