At the moment I'm going through a £75 bag of resin a month, which I get from pure freedom, I only have 150 customers so not even full time yet as from the picture I have 2 vessels a 40/40 filter and the pre filters which get changed every few months. I do also regularly flush the tank for 30 mins. Any help as to why my ppm is going so high so often would be much appreciated. It went from 0-6 within a day then the next day up to 26ppm this was only a week after changing the resin. Tap ppm is just over 300. Thanks