Out of personal experience I would stick to 2part and get a dosing pump, you can find them for $50-60 each. Kalk significantly speeds up wear of your pumps and other equipment but it can be very effective. Also, i would not use it if your PH already runs high since it adds Alk as well as Ca.
In a nut shell(I am not a chemist but this is what I did with my tanks):
1. Get a 5g bucket and add 2 tsp of kalk, stir it carefully and cover with lid.
2. let it sit for about 2 hours+ (i'd do overnight) until the water is not cloudy anymore.
3. after letting it sit, carefully drain off the clear water trying not to disturb undissolved kalk at the bottom ( it reaches a saturation point and the excess ends up at the bottom)
4. clear water is your top off or drip, don't ever just dump it in to the tank/sump, it has to be added via drip or auto-topoff that systematically pumps throughout a period of time.
5. Follow this link to a calculator, fill out the fields and choose "lime water" from drop down, it will tell you gallon/day that you need to add.
Reef Chemistry Calculator
6. If your gallons needed exceeds amount of daily top off, then you can add a tsp of 5% table vinegar to the bucket when you make a batch of new top-off and that will increase the concentration on make it more potent ( long explanation in terms of chemical process)
7. You can use this is addition to dosing 2 part if needed.
8. TEST OFTEN, at least until you establish a system. Start slow and ramp it up as needed.
9. keep an eye on your magnesium
10. kalk binds phosphates and even though its desirable to keep them low, they are needed for coral nutrition and there is a possibility that corals may need to be fed in supplement to normal feeding. depends on your tank.
11. there is something about dosing too fast and water turn cloudy but I forget, never happened to me. Basically stop dripping if it happens
12. It will ruin your pumps unless you wash them in vinegar pretty much monthly. You'll see a coat of calcium on your heater, plastic parts and especially anything that produced any sort of heat.
hope this helps