Why does Epsom Salt contain calcium?

[erwin123]

I had thought that something marketed as Epsom Salt would contain only Magnesium Sulfate. However, I have come across two different packaging of Epsom Salts where Calcium is indicated as an ingredient. Does this suggest that we need to be careful when buying Epsom Salt and make sure we only get something that is 'only' Magnesium Sulfate?

 

[erwin123]

Thanks - g /mg my eyesight is slowly deteriorating - need to look at my fish tank more, and computer screens less

 

[dw1305]

Hi all,

Thanks - g /mg my eyesight is slowly deteriorating -

Same for me, I looked at it about three times before I noticed the units. I was thinking "well this is wrong", but I still didn't twig why.

cheers Darrel

 

[MichaelJ]

If your targeting ~10 ppm of Mg with this compound, the listed impurities in there will only amount to 0.04 ppm of which 0.0063 ppm would be Calcium, 0.0042 ppm Sodium, 0.0082 ppm Chlorine, 0.021 ppm Potassium

I don't think (m)any of the compounds we buy in bulk for our tanks are much purer than that.


Cheers,
Michael