4 Stage Value Plus 75GPD RO/DI System - Bulk Reef SupplyBRS 4 Stage Systems are perfect for reefers who have water treated with chlorine or relatively clean well water. The 4 stage systems are self contained on a single bracket making them ideal for tight spaces or where a non permanent connection may be required. Installing a RO DI system only takes a few minutes and can be done very easily without any permanent modifications to your home or the plumbing. 4 Stage Value RO DI Features: Multiple source