My pool is clean and up and running at a temp of 50. Just opened it last week. There is plenty of salt in it - my test said 3200 ppm (although the chlorinator's low salt light is on). When I add the DPD powder to test for FC the water stays totally clear. Last week (water was 56degrees) I had FC of 4. Is it possible that my test this week is not reliable due to the cold temperature? Could the powder have gone bad in the past week? Or is it accurate that I have no chlorine? The CYA level is also coming up as 0 (unmeasurable below 30). I've been maintaining my pool for 2 full years and this is a first for me. Thanks in advance!!!