Also, unless you have a pH meter (calibrated), using the tests that require comparison to a color chart is probably +/- 0.4 or so. Which is to say, more or less useless... If your Ca/Alk are good and your tank is well oxygenated (good water flow), you probably don't need to worry about pH.
Since your ca/alk usage is probably pretty low, I'd go with Randy's two-part (I'm happy to give you a few cups of Dowflake and you can get baking soda at the supermarket). Dose whatever is required to get your Ca/Alk to ~400/~10-11dKH (or whatever you feel is appropriate for your tank). Then check your Alk again after a week - add whatever it takes to get your Ca/Alk back up to the previous week.. As long as you're not adding/removing much livestock from your tank, the amount you need to add should be pretty stable.
However, if you don't have much SPS/LPS/No clams, just doing 10-20% water change/week will probably keep your levels within reasonable boundaries.. In my main SPS tank, I test Alk daily, but I suspect that my coral-inches-per-gallons-of-water ratio is somewhat ridiculous. It is almost like having a nano again!