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Deionized Water


  1. large-scale DI units
    by wrisch/ (Lisa Wrischnik) (Wed, 3 Dec 1997)
  2. water question
    by wrisch/ (Lisa Wrischnik) (Fri, 7 Nov 1997)

large-scale DI units

by wrisch/ (Lisa Wrischnik)
Date: Wed, 3 Dec 1997
To: apisto/

Hi folks,
Sorry I didn't get back to this sooner - things have been a little hectic

The fellow I'm married (Gregg)to has a DI system set up by the Culligan
company in his lab.
Gregg had set-up costs of about $300, but he was told it was due to having
to fix the plumbing in his lab to make it compatible with the system.
Tanks are
$60 (one tank w/ mixed-bed resin for both cations and anions), but there is a
$20/month "maintainance/rental" fee.  His tank, which he shares with one other
lab if I recall correctly, lasted a year, and he claims he wasted a lot of
water flushing the system out (due to some plumbing-related problem).  Tap
water in the area runs from about 120-200 ppm, so obviously the lifespan of
the tank will be less the harder your local water runs.

Gregg also said that the system delivers water at pressure, and that there
is a resistance meter hooked in to the system to let you know when the tank
needs to
be replaced.

We are seriously considering setting one up at home, but just havn't gotten
around to doing the legwork (let alone figuring out where to put it, etc.
Maybe we'll wait until we can afford the fishroom).

If anyone finds out any more, please let me know.


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water question

by wrisch/ (Lisa Wrischnik)
Date: Fri, 7 Nov 1997
To: apisto/

Hi gang,

Bob said:
>Ion exchange resins have a sodium-containing salt that readily gives off the
>sodium and binds calcium, magnesium, and other heavier metals, in an
>"exchange" process.  While the water tests soft for GH and KH, and acts
>"soft" in the presence of sudzy things like soap, it may not be suitable for
>some soft water fish.  Most of them will do quite well in it, but some are
>sensitive to saltiness, and may not like this water much.  Years ago, I heard
>of a DI unit that had a second stage, which electrically removed the sodium
>compounds, giving a water quality as good as or better than RO, but I am not
>sure they are still available.
You could also just get a DI unit that exchanges cations such as Ca+2 and
Mg+2 with a hydrogen ion (H+) and anions (like nitrites and Cl-) with a
hydroxide ion (OH-). You end up replacing all the "bad" ions with,
essentially, the components of water (H20). This is what I have and it
works pretty well (I charge up the resins every few weeks or so using
hydrochloric acid (sold as muriatic acid for pools) or sodium hydroxide

I know that companies like "Culligan" will set you up with a water softener
that replaces cations with sodium, but I have been told that these
companies can also set up a DI system that replaces with H+ and OH- (the
guy I'm married to has one of these to give him DI in his lab). May be
worth the initial investment for some people (I think maybe $300 to get
started and then paying for the replacement tanks every so often -
depending on your local hardness conditions).
I can find out more if anyone really cares ;).


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