I like to use NSW S.G. 1.026,lots of synthetic salt mixes are low in Magnesium and by mixing full strength,the levels will be higher.Baking soda will slightly lower PH as mentioned by Repto,I use it unbaked 2-3 times a wk.As well as Calcium Chloride to balance the alkalinity provided by baking soda.12ml of liquid calcium(kent) is what is needed to balance out 1 tsp of baking soda.Alkalinity(bicarbonate/carbonate) is the limiting factor in calcification in stoney corals.Many test calcium often and strive to keep it at 420ppm.By monitoring alkalinty depletion,you can pretty much tell where your calcium is at because they are tied together.Once the 2 levels are balanced it becomes much easier to maintain without much testing.I only test calc monthly and its been at 420ppm,i test for alk 2times a week(in my new tank)and by adding a balnced baking soda/CaChl supplement,the levels have been consistent.