I used dolomite in my calcium reactor to replenish lost magnesium. I use additives only to correct levels (occasionally) I haven't dosed anything on a regular basis in over a year (just water changes).I used 2 part before that with a doser. Was just as good, but my demand outgrew what 2 part could provide (without spiking the PH too high). It was only then that I switched to a Calcium Reactor.Well yes and sometimes, cal rx is not the saving grace. You still need to test and monitor your tank usage of chems.
Regular water changes will help keep strontium levels within reach of minimal dosing .Your basic goal is to replenish everything that gets used by your corals, to NSW levels.As your corals grow , they use those chems more aggressively, so you gotta give them what they used at the correct ratios.