First thing to know is, most tap water is "hard water", which has lots of
calcium and
magnesium dissolved into it. This is good for your tank and your fish!
Hardness is measured in "parts per million" of calcium carbonate, and the "general hardness" of the calcium (
GH). "Soft water" has under 135
PPM and 4 to 8 gH, while "hard water" has more than 200 ppm and 12 to 20 gH. You'll want to find a test that helps you measure the ppm in your tank: a "general hardness kit" measures gH, although you can often get a good answer with a phone call to your water utility, whose job it is to keep track of hardness.
I dont really know what is ment by 'water hardness = o' does that mean it's really soft water? If so I've read that you can increase the water 'hardness' by just filtering it through crushed coral or dolomite. A stable 'hardness' is impotant as well, alot of change can cause stress!
Apparently a really soft water tank is dangerous because the
pH will fall fast, and go low, which can be fatal to fish.
Good luck!
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