I have maintained my pool for 15 years with no algae problem, except when I was occasionally lazy with maintenance. The pool sipped chlorine. This year, I had a garden of algae, uncontrollable. Lowered phosphate, no real effect. Chewing up 4 gallons of chlorine a week, plus tablets. Just added PoolRX 1 week ago based on the recommendation of a friend. Chlorine consumption has stabilized, so far so good.