@CTBarrister Those fizzy tablets look extremely expensive to me. I take one tablet of calcium (500 mg; need to add it because of reduced bone density) in the morning and one or half a tablet of magnesium (250 mg) in the evening. That's about 2/3 of the recommended daily amount and what 10 of those Nuun tablets contain. A pack with 17 tablets costs less than 1 € each in the local supermarket (store brand).
By the way, if you break the tablets into two halves, they may fit into the bottle.
Salt (sodium + chloride) is what I add according to my blood levels. At the moment I need 2 g a day (in addition to normal food intake). I usually add it to my meals in the morning and in the evening, only 0.5 g at a time so I don't get nauseous. That's simple natural brine salt.