Water Hardness & New Tank

[bbleho]

Hi All, new here. I've been fishkeeping for some years now, though I'm no expert! I've just set up my 10 gallon aquarium today. I've had plants in it for the past year, but just set it all up for fish today. This is going to sound silly, but I can't figure out how hard my water is. The specs from the city are: 81 ppm calcium carbonate (pH 7.44). I've searched online and am getting conflicting responses ranging from soft to moderately hard. I'm confused!

Anyways, if it is hard, I've been reading here and elsewhere that I shouldn't be overly concerned unless the fish are ill, etc. I was thinking of getting a school of rummy-nose tetras or harlequin rasboras and 3 of something like scissortail rasboras. Any thoughts? Or would I be better off purchasing swordtails and mollies??

Thanks in advance!

 

[bbleho]

It seems like most sources are saying moderately hard, so I suspect I was reading the others wrong (wrong units perhaps). But please confirm! Thanks

 

[Mr Bliss]

When they say "moderately hard" they usually mean general hardness that comes from primarily calcium and magnesium ions in the water. Depending on the amount of sulphates (since Mg and Ca salts predominantly come as either sulphates or carbonates) in the water, this may or may not be similar to your Carbonate hardness, which is a more relevant parameter for aquarists.

Carbonate hardness is sometimes, especially in older sources, expressed like that: "as calcium carbonate". It's a bit misleading, since calcium carbonate isn't the only salt responsible, but this is in fact what common KH measurement scales are based on as well, ie. if your carbonate hardness is 60 ppm according to some test, it actually means "corresponds to 60 ppm of calcium carbonate". In other words, the concentration given in the specs is directly comparable to the ppm given by any hardness or alkalinity test.

17.9 ppm corresponds to 1 dKH on the German scale, so your KH is ~4.5, which is fine.