08-23-2012, 09:06 PM
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Originally Posted by Byron
As you've correctly mentioned, this instrument is measuring all TDS, which includes the mineral salts (calcium, magnesium, etc), common salt (sodium chloride), water conditioners, plant fertilizers if any, fish foods, and any other substances entering the water (additives, etc.).
The normal terms of soft or hard water generally refer to the hard mineral salts and the GH test kit measures these. But the TDS from the other mentioned substances also affect fish. Soft water fish are sensitive to these, so they should be as minimal as possible.
The difference in numbers between your tanks is indicative of the TDS some substances contribute. You mention "salt" for the livebearers, if this is common sodium chloride, this is best left out as it can be detrimental. Mineral salts from calcium, magnesium, potassium, etc are what the fish require as "hardness."
When you refer to "mineral salts", would that be regular aquarium salt? If so, then if I use salt in my livebearer tanks then that alone will provide the hardness they need?