Calcium and calcium hardness

[Jim Bell]

Maybe a daft question
Are calcium and calcium hardness the same thing
Having trouble locating a hardness test but can get a calcium test

 

[ajw22]

Yes, they are the same test.

 

[Jim Bell]

AWJ22 thanks

 

[mgtfp]

Just make sure you get the units right. Aquarium test kits often tell you the results in ppm Ca, but for pools ppm CaCO₃ is used.

A result given in ppm Ca needs to be multiplied by 2.5 to convert it to ppm CaCO₃, because the molecular weight of Ca is 40, and the molecular weight of CaCO₃ is 100.

If the test result is for example 100 ppm Ca, then this equivalent to 250 ppm CaCO₃.

 

[Jim Bell]

Thanks for the heads up mgtfp