If no calcium hogs, would stick with water changes and ignore the test kit which could be bad. Adding Mg will depress Ca, and pretty soon on a dwindling spiral. Keep it simple and let the tank mature with as few changes as possible. The corals will settle in and take off.
Just for good mesure if you are interested, please list off all water parameters, flow level and from what, if use RO water, how frequent water changes, type filtration, and anything else including inhabitants. Pics are helpful.
One think to remember, corals do not like lighting changes, Going from 175s to 400s will bleach out almost any SPS, untill it goes back to brown and THEN starts to color back up.
If all else fails, perhaps somebody could swing by and take a look :>/