Am having a mare with my resin which is costing a fortune. Any help appreciated. Issues listed below: Have just had to replace resin after 2 months. I only produce 150ltrs a week so sound like its gone too quick. When I bought the vessel from pure freedom and they filled it it lasted about 6 months before going to 16ppm. When changing resin do you always get rid of all that is I'm the tank, wash it out etc and start from scratch? Both times I have refilled, this first time I've filled up its produced 8ppm so have undone it, put more resin in and got 0ppm Does anyone just top resin up? I don't understand what happens to the resin to make it unusable? Any help appreciated, I'm doings nut here! And my bank balance at £70 a bag!