If you are getting into SPS now, I highly suggest switching to a more balanced 2 part dosing system like BRS 2 part, Reef Supplies 2 part or B-Ionic.
http://www.reefsupplies.ca/online-store/2-Part-Dosing/ Something along those lines. I don't know what the concentration is of the Purple Up or Seachem products.
You can safely increase Cal by 100 and ALK by 1 Dkh in the span of 24hrs. Don't try to do it in one shot though as it can potentially cause issues. Everytime you dose ALK, you will also increase your ph levels so it is best to dose ALK during lights off when ph is at its lowest point.
To figure out what your tank is using, you need to test once. Record your results and then test again at the same time the following day or 3 days even if you want more accurate results and then just divide by 3 and that is your daily consumption. Then use the BRS calculator and figure out how much you need to dose everyday. There will be a lot of testing for the first week or so and tweaks until you get it just right.