I give starting dose recommendations here (used in the absence of limewater; start a somewhat lower if you continue it)
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php
specifically here:
http://reefkeeping.com/issues/2006-02/rhf/index.php#15
Dosing Instructions
The dosing instructions are basically the same for each recipe, although any given aquarium will end up using about twice as much of recipe #2 as recipe #1 to add the same amount of calcium and alkalinity.
To initiate dosing, first adjust calcium and alkalinity to roughly their correct ranges. This may require a substantial dose of just the calcium part if calcium is low (e.g., below 380 ppm). I would suggest targeting calcium between 380 and 450 ppm, and alkalinity between 2.5 and 4 meq/L (7-11 dKH; 125-200 ppm calcium carbonate equivalents).
This calculator shows how much of what parts to add in order to boost one or both of the parameters by a certain amount:
Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html
Then, once things seem roughly correct, select a starting daily dose for routine dosing. Here are some suggested starting doses, but the exact values do not matter much. The suggested doses apply to both recipes.
After a few days of dosing, note whether alkalinity is low, high or on target. Only bother to test alkalinity, not calcium, during this period, because it is much more sensitive than calcium to over- or underdosing. Adjust the dose up or down as necessary to increase or decrease the alkalinity.
Once you have determined the proper dose, continue it until there is a substantial reason to adjust it (such as falling alkalinity as the corals increase in size). When adjusting the dose, raise or lower both of the recipe's parts together.
Resist the temptation to keep jiggering calcium and alkalinity independently. They will need occasional corrections, but that should not be the normal course of dosing unless there are substantial outside influences, such as water changes with a salt mix that does not match the tank's parameters or an error in making the mixes.
Check alkalinity fairly frequently to make sure the dosing continues at a suitable rate. Check it maybe once a week to once a month (or less as you get more experienced with the system and the tank). Check calcium once a month to once every few months to make sure it continues on track.
Remember to add an appropriate amount of Part 3 each time you finish adding a gallon of Parts 1 and 2.
Tank Description:
Suggested Starting Doses:.......Recipe #1.......Recipe #2
Fish-only with live rock .......0.1 mL/gallon.......0.2 mL/gallon
New tank, few corals .......0.2 mL/gallon.......0.4 mL/gallon
Low demand.......................0.3 mL/gallon.......0.6 mL/gallon
Mixed tank .......................0.5 mL/gallon........1 mL/gallon
Heavy demand (SPS corals)..1 mL/gallon...........2 mL/gallon
