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Sv: Aquatic Plants Digest V3 #1170
This posting hasnīt appeared. Possibly because of a spam-block in my account/properties.
>Date: Wed, 21 Jul 1999 10:40:28 -0400
>From: "Louis Lin" <lhclin at aw_sgi.com>
>Subject: Re: KATI / ANI vs. RO / DI
>I am getting the feeling that KATI is a great solution for people with hard
>and alkaline water. KATI will replace the calcium and magnesium ions with
>H+ and the H+ will neutralize the carbonate in the water to reduce pH and
>produce CO2. And the KATI is rechargable with HCl, which is commonly
>available. And there is no waste water.
>This sounds too good to be true. Is there a catch?
Yes, there is a catch. When a "strong acid ion exchanger" and that is what KATI is, is used, it takes "all" the cations in the water in exchange for hydrogen ions. If all the cations in your tap water comes with only carbonates and hydrogencarbonates as anions, the KATI is very suitable as stand alone for making water for rainforest types by turning the carbonates and bicarbonates into carbon(ic?) acid, with a pH of around 5. After good areation this rises to maybe 6.5. But this kind of tap water is not very common. Mostly there are sulfates, phosphates and nitrates too as an ions. These will, in conjunction with the hydrogen ions make the appropriate strong acids resulting in a very low pH ~2. There fore the ANI.
But AquaTechnik, who makes the KATI/ANI makes a "KATI S" too. That is a "weak acid ion exchanger" taking the cat ions only of the weak acids (carbon(ic?) acid) resulting in slightly acid water with a alkalinity close to zero and a reduction in TH corresponding to the original amount of carbonate/bicarbonates. When water is as it is many places in the northern hemisphere ( carbonates/bicarbonates being responsible for 1/2 to 3/4 of the total hardness) the use of KAT S is an economical and easy way of making water suitable for "black-water" fish. And for breeding them, too. So, in many cases, the use of KATI/ANI, like the use of RO, actually is overkill.
ole.t at larsen_dk