It's better to have too soft water than too hard i believe.
Except for fish that must have hard water eg the common livebearers, Rift Lake cichlids etc
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Yes Barbara you have soft water, softer than mine.
Those two figures I asked for, fish sites tend to use different names for them. So mg/l calcium carbonate is the same as ppm in fish profiles; german degrees is the same as just plain degrees or dH in fish profiles.
Seriously Fish
http://www.seriouslyfish.com/knowledge-base/ is the best place to look up fish. Some of the profiles give hardness as ppm, some as degrees or dH. Your hardness is 50 ppm and 2.8 degrees/dH
If you look up
cardinal tetra you'll find they need water hardness 18 to 215 ppm, pH 3.5 to 7.5 and temperature 23 to 29 deg C.
White clouds need hardness 90 to 537 ppm, pH 6.0 to 8.5 and temperature 14 to 22 deg C
The pH can be a bit outside the fish's range as that is not as important as hardness.
So straight away we can see that your water is perfect for cardinals but a bit too soft for white clouds. And their temperature ranges do not overlap.
Then we need to look at minimum tank size. For cardinals it is 60cm wide x 30 cm front to back; and the same for white clouds. Is your tank that size?
If it is smaller, look at
ember tetra. This needs a tank 45 x 30 cm, hardness 18 to 179 ppm, pH 5.0 to 7.0, temp 20 to 28 deg C.
These are just examples to show how to put together a group of compatible fish that are suitable for a particular tank and water parameters. You do have plenty time during cycling to create a wish list
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