Kati Ani de-Ionization is a preferred method for water and is more efficient and can tend to give you a purer end product than traditional reverse osmosis systems and if you ever thought they were too expensive, ReadyAquatics.com has some units on sale for a great price. Besides making your water more pure, other benefits of Kati Ani systems are not really needing sediment or prefilters, not producing waste water, and the cation (Kati) portion can be regenerated. Each system comes with two reactors plus the amount of media needed for each part of the system.
For the Kati Ani Model one that is suggested for systems up to 100 gallons, the cost is now just $116.98 (marked down from $179.99) and includes one liter of resin. For larger systems you can get the Model Two for $168.98 with two liters of resins (for tanks up to 200 gallons), the Model Five for $361.98 with five liters of resin (for tanks up to 500 gallons) and the Model 10 for $611.88 with 1o liters of resin (for systems up to 1,000 gallons). Check out the ReadyAquatics website for more information.