Softening water with cation resin: how it works, how to build a softener and how to regenerate it with salt
The Purolex PRC107E resin specification (equivalent to Purolite C100E) in plain words, how much water a litre of resin gives at your hardness, how to build a softener, salt regeneration step by step with amounts of salt, water and time, whether softened water is safe to drink unboiled and whether it protects against kidney stones, other resins and where to buy them.