This is what I was going to say, too. It has nothing to do with being a LCer. Practically everyone is deficient. Water softeners and drinking a lot of bottled water that isn't remineralized - probably another reason.

I take Jamieson brand Mg (and now cal/mag). It has 3 or 4 different forms of Mg. The chelated brands are probably better, but I'm on a budget.

How much water vs salts you need to stay hydrated probably depends a lot on your climate. Where I am, it's humid. Where Mama Sebo is, it might be dry desert. (Is it?) I've worked in both extremes. Hmm. That might be my reading for today, to figure out how we sweat and hydrate differently when sweat doesn't evaporate like it should (high humidity).