My Mississippi Lime Company's lime is food grade calcium hydroxide (I buy it in a bulk from Bentagg, too.) It adds both calcium and alkalinity to salt water in a balanced manner.
Calcium reactor does the same thing. I use lime water to raise the pH that Calcium reactor tends to depress with the addition of CO2. They really complement each other well. They also lend itself well to automation. However, 2 part solution method works well, and I believe you can automate it well with Litermeter III system or something like that.
I use Magnesium chloride (Magflake) and Epsom salt every now and then to increase the magnesium level to keep the calcium level stable. I got my first batch of Magflake from Beaslbob and I bought some from Bulk Reef Supply later as well.
Tomoko