The Mixed Bed Deionization Cartridges are designed to remove nearly all electrically charged contaminants (cations and anions) from the water. D.I. cartridges are often used as post filters to reverse osmosis systems to produce ultra pure water. Although it is also common to use them as stand alone filters. When using a TDS meter, you will notice that your TDS (Total Dissolved Solids) will drop to near zero ppm. These filters come in a reusable cartridge. Once the resin is exhausted, you may just purchase DI resin and refill your own cartridge. Removes/Reduces : Nitrates Phosphates Silica Ammonia And other charged contaminants Specifications : Micron Rating: 10 Nominal Dimensions: 20" x 2.5" Total Weight: 3 lbs Operation Temperature: 40F to 100F Max Recommended Flow Rate: 1 GPM Filter Media: Mixed Bed Resin Filter Life: 11,000 mg/L or 640 GPG* *Filter life in gallons can be calculated by dividing 11,000 by the feed water's TDS in ppm (11000/XX ppm = Filter Life in Gallons).