There used to be a resin calculator on gardiners site but it's gone now they have a new website... Does anyone know how to calculate resin usage? My tds is 200 ish, how many litres of pure would I get from a 25l bag of resin?? I want to experiment with just using a resin vessel on a garden tap for conservatory cleaning. When I do deep conservatory cleans I use straight tap water to do 95% of the work and then just a quick brush and rinse with pure. I'm sick of filling jerry cans in my kitchen!!!!!!!!