2-stage Heavy-duty DI unit for salt water Aquariums and reefs   Model: DI-210   Application: The purpose of the DI unit is to further reduce the mineral content of water after RO system.  If you want to achieve very pure water, very low or “zero” TDS reading for large amount of water, then this is the unit to get. This can be used with any reverse osmosis system or RO+DI system, also use with Watergeneral RO585, RO6102DINT, RO6100+DI   NOTE:  This DI unit is used in conjunction with an RO system or RO+DI system. NOTE:  If connect directly to tap water, the DI resin will be used up very quickly.  (not recommended)   Capacity:   2 lbs of DI resin.  It will treat about 3000-4000 gallons of RO water, but actual capacity depends on tap water TDS and RO water TDS.   Features: Two 10” cartridge type DI filters with color changing Nuclear-grade DI resin. Clear Filter Housing to observe color changing DI resin: when the color changes from green or light brown (when new) to dark brown and black (when exhausted), it is time to replace the resins. Refillable filter cartridges:  you can open up the filter cartridge and refill the resin inside Vertical placement:  DI filters stands upright can reduce the effects of channeling.  It’s more efficient, and removes more minerals. Includes a steel mounting bracket:  White powder-coated steel bracket is used for mounting of the unit on the wall or cabinet   What’s included in the unit: DI unit with clear filter housings and 2 DI filter cartridge already assembled Filter housing wrench 10 feet of tubing, ¼” ¼” compression fittings on the inlet and outlet