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. "TDS" is known as "total dissolved solids" which means are dissolved salts. Dissolved salts in water have charges of a positive or negative ion. Any charged ion will be counted to the TDS level. When using a TDS meter, you will notice that your TDS 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: 10" x 4.5" Total Weight: 3 lbs Operation Temperature: 40F to 100F Max Recommended Flow Rate: 2 GPM Filter Media: Mixed Bed Resin Filter Life: 12,000 mg/L or 700 GPG* *Filter life in gallons can be calculated by dividing 12,000 by the feed water's TDS in ppm (12000/XX ppm = Filter Life in Gallons). Additional Details ------------------------------ Product description: 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. "TDS" is known as "total dissolved solids" which means are dissolved salts. Dissolved salts in water have charges of a positive or negative ion. Any charged ion will be counted to the TDS level. When using a TDS meter, you will notice that your TDS 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: 10" x 4.5" Total Weight: 3 lbs Operation Temperature: 40F to 100F Max Recommended Flow Rate: 2 GPM Filter Media: Mixed Bed Resin Filter Life: 12,000 mg/L or 700 GPG* *Filter life in gallons can be calculated by dividing 12,000 by the feed water's TDS in ppm (12000/XX ppm = Filter Life in Gallons).