Yeah. Well i tested calcium alkalinity and magnesium after i mixed some brand new saltwater. I made 3 five gal buckets all to 1.026 salinity and all of my results were consistent at calcium 470, alk 10, and mag 880. It looks like if i can get my levels correct in my tank then i will truly only need to dose mag to about 1350. At least until i get any demanding corals.Wow. Alk is pretty damn high. I think most limit Alk to 12dkh max. CA is also way high. It's pretty useless to dose past about 440/460 if I remember correctly. Goes to show how off your API test kits were.
At this point, I would get both your ALK and CA back to a normal level with some daily water changes for the next few days.