Bulk Reef Supply 6 Stage Reverse Osmosis Systems represent the leading RO/DI systems in the industry. We only use the best DOW membranes, BRS Universal Carbon Blocks, and GE Sediment Filters. The BRS 6 Stage RO/DI systems also come with dual DI canisters making them perfect for removing chloramines, and chlorine. Or if you have other hard to remove elements like phosphates, nitrates, silicates, etc. We offer three different levels of systems each providing additional components over the previous. We specifically design our RODI systems for use on reef tank and other types of marine aquariums.