Deionization vs. RO

From: Steve Hinkson (
Date: Wed Dec 15 1999 - 00:17:40 PST

Date: Wed, 15 Dec 1999 00:17:40 -0800
From: Steve Hinkson <>
Message-Id: <aabcdefg4141$foo@default>
Subject: Deionization vs. RO

To whomever cares...*grin*:
Deionization vs. RO is apples to oranges.

Reverse Osmosis (RO) removes the Total Disolved Solids (TDS), at least for our
purposes, as long as the membrane remains impermiable to the molicules. That
length of time depends on the water PH and hardness to begin with.
Deionization (DI) precipitates out a percentage of the TDS, depending on flow
rate and the strength of the DI unit.

Your Co-operative extension agent in the US can tell you the average TDS of
your tap water. If you're below 100 ppm, don't bother with any. Between 100
and 450, either unit will do for most CP, but at the upper end of that TDS
range, deionization home units won't make really good water for the salt
sensitive plants, and the larger comercial plants that will, cost a fortune !
Above 450 ONLY RO will be sufficient, and above 600, expect to change the
membrane more than once a year.

My local tap water runs from a late Spring low of 550 ppm to a late Fall high
of 750 ppm.

Merry Christmas, and a happy 2000,
and I hope the happiness lasts into the new millennium !

Drop by and see me at :

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