You’ll have to start using a calcium chloride supplement every so often to keep up with coral and coralline algae growth (what makes our rocks turn purple). Something like this is good to have on hand to in order to make small adjustments to keep your calcium range in the “goldilocks zone”.
Another option until calcium demand becomes too great is a “reef salt” mix and a consistent water change schedule coupled with proper feeding amounts. When mixed with water, these salt mixes will have increased levels of alkalinity, calcium, magnesium and beneficial trace elements. One of my favorites is Tropic Marin as they tend to mix around 7-9 dkh depending on the exact mix you get, which is a pretty safe range. For example, this is what I would use on your setup if I were doing a 10% weekly water change (spread this out during the week if possible, it’ll keep your tank more stable and keep your inhabitants from being shocked by rapid water parameter changes):
Bio-ACTIF: Ca: 430-450 ppm, Mg: 1300-1350 ppm, Alk: 8-9 dKH, plus carbon dosing (gotta run a protein skimmer to benefit)
Some salt mixes, such as Red Sea can mix at 11dkh or higher, which is great for coral growth but can be more demanding to use as the tank has to be fed more to prevent burned coral tips and necrosis. The lesson here is to always make sure to check the specifications of a salt mix.