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Q&As since 1989


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De-ionizing water

We would like to de-ionize our tap water to replenish our daily evaporation of our nickel tank. If we evaporate lets assume 10 gal.a day. do we use anodic or cathodic - and at what voltage-do we need any special salts- and how do we test the results ?

Very truly yours and thanking you in advance,

Leonard Vogel
- Los Angeles, California
2003

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The best way to make DI water is to use resin columns, both anionic and cationic. Systems should be reasonable for the volumes you mention. To test the water you measure the resistivity of the water; a good rule of thumb is 2 megohm-cm.

James Totter, CEF
- Tallahassee, Florida
2003

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2003

For only 10 gallons, or even a hundred gallons per day, your most economical choice is to use an local exchange tank service, or to purchase a small RO system. You can measure the quality with a conductivity or resistivity meter, but most small systems use a simpler device that is just a red/green LED that is set to turn from green to red at a set resistivity, usually a resistivity 1 meg-ohm-cm, or a conductivity of 5-50 microSiemens. A conductivity of 50 microSiemens is only 25-30 mg/l of TDS, so even at this quality, about 95% of the TDS in LA water has been removed.

Lyle Kirman
consultant - Cleveland Heights, Ohio