As always, great advice from Dave.
I don't think it's been addressed yet (forgive me if it has), but why is it that you're considering kalk? The reason that most people say to be careful with kalk is because if you're not using it for the right reasons, or in the right manner, it can easily cause troubles. Ca of 400 isn't too bad at all, and unless you're trying to boost it intentionally for SPS growth. Please don't misunderstand, kalk is a great no-nonsense way to maintain Ca and alk, but you need to know why you're using it as well as be aware of the idiosyncrasies of kalk. If it's only for one of the ancillary benefits such as raising pH, I would strongly advise against using it. IMO, the purpose of kalk is Ca/Alk control, with pH elevation as an ancillary benefit, not the other way around.
If I were dripping kalk, I would start with a very low concentration, perhaps 1/4 tsp/gallon, and I'd mix only enough to last 2 - 3 days. I would set the drip rate very slowly to start with. If you end up needing more kalk, increase the drip rate. If you're meeting your top off demands with the kalk mix and you still need more kalk, try increasing the kalk concentration and dialing back the dose. You'll eventually dial in on a concentration that works for you and allows you some topoff room as well.
Again, I wouldn't discourage you from using kalk because it's a great way to maintain Ca/Alk, but there are a LOT of little gotchas that you have to keep in mind. Personally, I'd stick with two part until you have a very solid understanding of how that works. It's hard to mess up two-part. Calculate how much you should use with a dosing calculator, start a little lower than that to give yourself some margin for error, and adjust as necessary.