Reverse osmosis systems remove 99% of all impurities from tap water used to fill the aquarium.  They help ensure that the fish are healthy and free from disease. These systems usually feature an intense three-stage, pre-filtration system that includes the use of filtration membrane and silica busters. Those looking to maximize the performance of their systems can buy add-ons such as level controllers, shut-off  kits, and booster pumps. Other accessories that can be purchased include the float valve kit, the shut-off kit, flush kits, and TDS meters. Most reverse osmosis systems usually come with a mixed bed filter, with the system filtering roughly about 95% of the particulates and the mixed bed system catching the rest. Owners also need to purchase replacement filters, as well as sediment, carbon, DI, and membranes when the system needs to be replaced with new filters. Aside from keeping the water clean, reverse osmosis systems make pH conditioners more effective because they leave the water with virtually zero solids, allowing the pH conditioner to work  more effectively.