Elaine T wrote:
///Owen\\\ wrote:
Reel McKoi wrote:

"RichToyBox" wrote in message
...

My ST is clear looking cylindrical crystals. The instructions that
came with it was to mix it, 500 grams (slightly over a 1.1 pounds)
with one gallon of deionized water,

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What is *deionized* water?


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To all intents and purposes deoinized water is the same as distilled
water. To distill water you boil it and condense the vapour. This
leaves the stuff dissolved in the water behind. To deionize water
you pass the water over a resin that removes any ions present.

Distillation - you remove the water from the impurities
Deionization - you remove the impurities from the water



Not quite. Deionization is mostly for removing salts. Dissolved
organic compounds, chelated metals, weak acids and other molecules
that are not 100% charged go right through a deionization column. Even
ammonia would go right through at low pH. Distilled water is
considerably purer than DI since only the water molecules evaporate
and everything, charged or not, is left behind. In sensitive
applications like biochemistry, DI water is generally unacceptable.

For dissolving thiosulfate to go in a pond, it probably doesn't matter
which you use. Distilled may be easier to find.
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You're right, of course, but if you start with tap water....