The KATI ANI units are Ion Exchangers which means they adjust water that flows through the resins by exchanging Ions. The resins give up some Ions and take in other Ions. This exchange can dramatically affect the chemical composition of the water.

The KATI and ANI are two separate Ion Exchangers that can be used singly or together depending on the desired result. This manual will explain the operating process and regeneration process for filtering tap or well water prior to adding to the aquarium. This will utilize both the KATI and ANI units in sequence and will totally de-mineralize the water. The end result is a very pure water with virtually no hardness or TDS (total dissolved solids) remaining in the water. KATI ANI units produce very consistent results and they are generally acknowledged to create 99% pure water. Reverse Osmosis at best is generally rated at 98% with variability of the results. Other advantages over RO include no waste of water (which is a significant cost savings), faster processing time (380 gallons/day), does not need high water pressure to operate, and no costly replacement of pre-filters, carbon block filters, and membranes.

Other functions the KATI and/or ANI units can perform are dependent on how the resins are regenerated. The regeneration process defines what Ions the units will remove from the processed water. The KATI unit alone can be used to soften water or to partially de-mineralize water. The ANI unit alone can be used to keep stable pH in a saltwater aquarium. It can also be used on a temporary basis to polish salt water (reducing Nitrate). Beside totally purifying tap/well water before using in an aquarium, the combined KATI and ANI system can be used to temporarily to reduce the total mineral content (including Nitrate) in a saltwater system, thereby reducing the need for water changes. In freshwater aquariums, the KATI ANI filtration can be used more often and could totally eliminate the need for water changes. The regeneration processes for these alternative uses are more complex and the operation of filtering an existing aquarium requires close monitoring.

The KATI (red) resin is the only resin that changes color as it depletes which indicates the remaining life for both sets (KATI and ANI) of resins. Regeneration is not overly complicated nor does it require expensive equipment or chemicals. However, the chemicals used are either very strong acid or very strong base chemicals, which can cause very serious injuries if proper processes are not followed. The KATI ANI resins are very high quality and have lasted for over 20 years in some systems.

The various models of KATI ANI run from model 1 through model 10. The model number stands for the number of liters the units hold. So, the model 10 holds ten liters versus the model 1 with one liter. This means that the model 10 will process ten times the water (with the same hardness) although at the same throughput speed. Likewise, the regeneration process will use ten times more regeneration chemicals in a model 10, but the regeneration time is the same.


The KATI ANI deionizers do not require sediment pre-filters or carbon filters. Many people still use these filters, which is fine. The sediment in unfiltered tap or well water will not clog or slow down the KATI ANI deionization process. Tap water with very high chlorine or derivatives have caused the KATI resins to bleach over time, which reduces the ability to visually determine the remaining life of the resin charge. Any type of granular or block carbon placed before the KATI ANI units will prevent bleaching.

The units are tall in proportion to their base so they should be either hung securely on a wall or braced to prevent falling if left standing. However you set up the units, remember that you need to periodically remove the units to regenerate yourself or send out for regeneration.

The units come plumbed from Germany with a standard 3/8" slip fit nipples. The recommended tubing is a 3/8" ID semi-rigid white tubing commonly used to connect automatic ice makers. The German phrase on each unit states that you should not use a hose clamp. The slip fit works well because the unit is not to be plumbed under pressure.

The KATI (red) unit is always the first unit to receive water from your tap or well. This then plumbs into the ANI unit which then plumbs to your purified water storage. There are two steps involved each time you place the units in operation (after each recharge). In the first step, you plumb the incoming tap water into the center hole of the KATI unit. Then you connect the hose from the outside hole of the KATI unit to the center hole of the ANI unit. Then the plumbing goes from the outside hole of the ANI unit to a sink or bucket. Run about 2 gallons of water briskly through this KATI ANI 1 set up.

After this, you are ready to re-plumb the units for continuous de-ionizing. It is simply a matter of having the water flow in the opposite direction within the canisters. The flow of water should be re-plumbed as follows. Incoming tap/well water to the outside hole of KAT, then center hole of KATI to the outside hole of ANI, then center hole of ANI to water storage.

It is always recommended to aerate purified water at least eight hours prior to adding to the aquarium or adding a sea salt mix. This is true no matter what type of filtration is used. Since the deionization process strips the water of all hardness, it is recommended that you add back some buffer and calcium so that it does not deplete these items from either the aquarium or the salt water mix. Raising the Alkalinity dKH to 6 would be a great start for the buffer side. The first time you purify a batch of water and then mix the sea salt, measure the calcium level eight hours later. Add calcium until you reach 400 ppm and note how much calcium additive you used. For future batches, add this amount of calcium prior to adding to the aquarium or mixing with salt. Please allow an hour or two between adding the buffer and calcium.

This system is not for everyone if you have CO2 issues it will also be a problem with the KATI ANI system. Regeneration of resin requires the use Muriatic Acid (31% Hrdrochloric Acid) and Lye (Sodium Hydroxide).
(Source: The Filter Guys)

I used the following for recharging:
Muriatic Acid: Klean Strip Clean (for etching concrete)
Lye: Roebic, Crystal Drain Opener

This unit is Model #2.
Comes with two "buckets" for recharging.

For sale: $100.00
Attachment 528

Attachment 529