Your doin fine, just do a few small water changes, and your params will fall in line. High calcium and High alk arent too serious, they will drop on their own over time. If your mag is low, your calcium will be too. most of the time, testing for mag is only done with specific types of corals that use alot of it, only other time is if your calcium drops, and dosing doesnt help. For most thing, a 10+% water change monthly will keep your parameters stable. If you are at all worried, make it 15% and do it every other week for a couple months.