So you're telling me that there is absolutely no difference other than price between those products? I'm printing this out and showing the LFS that a chemist who has studied this agrees with me and that there is no difference in the ingredients that make the products up. Correct?
FWIW, I am a chemist and I have studied these products in detail.
Here's my assessment from many other threads:
Unfortunately, kalk+2 is a very poorly designed product that won't work. It has very little magnesium in it (no more than is in ordinary lime: he is just labeling an impurity as a plus), but even that will precipitate out in limewater as magnesium hydroxide.
Really, this is a pitiful product. Not enough magnesium to be useful even if it worked, and it won't work.
It is a marketing gimmick.
I show in the article linked below that bulk supplied calcium oxide and hydroxide have that amount of magnesium or more already in it.
Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm
Chris Brightwell may be adding strontium to the kalk+2. However, it appears that despite claims in the past, strontium is just not a useful supplement for most reefs. Most people who dosed it and stopped see no difference, and there is no demonstrated need for strontium in most inverts. If, however, you want strontium for some reason, it may be a fine source.