Yes, val, look on the side of the bottle - if it ends in an 'ate' that isn't 'carbonate" you're fine

And potassium is no longer considered a cure for these cramps - it used to be, however, may years ago. Potassium is one of the big 3 LC supplements and it does help you feel better, but it's not going to effect leg cramps. However, if you have a difficiency in magnesium while you're taking your potassium you will not get the full benefit of it - you need the magnesium so the other minerals / salts can work.

Val - if you have been told not to take potassium then do not take it.
Nat