How to to raise calcium without affecting alkalinity?

[samrggzy]

So for a few weeks now my calcium has tested at 280-310 which I obviously would like to get up to closer to the 400-450 range. The only thing is my alkalinity has been fine at a steady 8.2. Is there a good way I can raise my calcium without it affecting my alkalinity?

 

[AFHokie]

Short answer, add Calcium Chloride. For more detail look at this article by RHF
https://reefs.com/magazine/chemistry-and-the-aquarium-solving-calcium-and-alkalinity-problems/