Alkalinity: 4 parts Baking soda and 1 part Soda Ash/Washing Soda. Soda Ash is made by baking Baking Soda in a glass baking dish at ~400 for an hour or so. Dissolve as much of this as will dissolve in purified water, then add it regularly along with doing Alkalinity testing to be sure of dosing the right amount. The desired range is 8-14 dKH or it's equivalent in meq/l or ppm.

 

Calcium: Dissolve as much Calcium Chloride (Peladow brand ice melt or CaCl2 from a chemical shop) as will dissolve in purified water. Dose it separately from the Alkalinity additive. Mixing the two together or adding them to the aquarium where they can mix too soon is ineffective and forms solid Calcium Carbonate in a chemical reaction typically described as "snowing".  But dose this Calcium additive on the same schedule as the Alkalinity, using an amount based on the need as determined by Calcium testing. 350-450ppm is the desired range.

 

Determining the correct amount to dose: For example, taking a 100 gal tank, I would start by testing the Alk and Ca levels. If either are out of the desired range, I would add  ~1/4 cup of the needed component solution, then test the next day to see what difference it made, if any.  Then adjust the dosage accordingly, testing and watching the levels daily (or weekly if you are lazy like me) until I had figured out about how much to add to replce what the tank is using.

 

Tip: Dosing at the same time as feeding, helps keep it fairly regular and consistent.

 

Tip: Reef aquariums can handle it if the dosage moderately exceeds the levels of the desired range. Simply stop dosing for a few days and let the tank take care of the extra through natural processes. If a large amount is accidentally added (dang kids) a partial water change can help alleviate a problem.