Jack, my reactor, and system, isn't as big as yours, but you can modify to get it tuned in. The nice thing about kalk stirrer's is that you can just add more if it uses more than you planned. Mine is pretty well dialed in, so my measurements are based on what i use in about 4 weeks. I clean out, and reload the stirrer every 4 weeks. After a month to 6 weeks of use, kalk isn't as "fresh" and has quite a bit of impurity's left, changing your actual dosing. You could just keep adding to the reactor, but the impurities will eventually build up.
I load my Kalk stirrer with about 1.5 cups of Kalk. I mix it as a slury, adding the 1.5 cups to about a quart or two of water (water first) mix it up, and add that to my stirrer (make sure you have enough room in the stirrer as to not overflow back into the system before it can settle to the bottom of the reactor).
I don't use my reactor for total top off. I have a secondary ATO that picks up the extra volume. I don't remember if your running a controller, but if you do, you can dial in exactly how much kalk your adding, and adjust when your CA, and ALK start to fluctuate do to coral growth, or general need for adjustment.
If you need more help, or want to know specifics, give me a buzz. I can swing by, and give you a hand.