i use pickling lime and vingear at rates of 40ml vin to 2 tsp pickling lime to 2L of water in my top off. makes my sps happy. I have a Ca reactor with CA media and mag media. I use to does calcium chloride for calcium but it scares me becuase the chloride can build up in an aquarium over time. both methods are cheap solutions to dosing. you could also use powder KH and Ca but it takes a lot of time and labor.

good luck, your corals will thank you.

kurt