This study evaluated alternatives to the traditional sulfuric acid/sodium heaxametaphosphate (SHMP) chemical treatment program for use in reverse osmosis (RO) permeators. The aim was to find a simpler, safer (no acid), and more economical scale inhibition program. The study was conducted by using a pilot plant reverse osmosis skid. Three 4-inch B-9 hollow fine fiber (HFF) membranes were used in each test. These were arranged in a 2:1 array, whereby the supply water was fed into two parallel modules and the brine reject from these modules was combined and fed to a third module. Three different commercial antiscalants were evaluated The paper discusses in some detail the fiber bundle autopsies of the membranes treated with different antiscalants. It also discusses the chemical analyses carried out and the detailed identification of the foulants found.