I jumping into the world of SPS and am looking at automating my calcium additions. Currently I do kalkwasser as a drip but tend to forget to check the jug. Do the kalkwasser reactors produce similar results to the calcium reactors without the need for CO2?
they both provide calc/alk, but calcium reactor has more control and its not depended like a kalk reactor is depending on how much evaporation you have ( which changes )
the calcium reactor can keep up with large additions too
for a light tank sps or softie tank, a kalk reactor would be ok, but when you mention automating that can only 100% be achieve with a calcium reactor because is the most finetuning device at the moment, good luck
Kalk reactors tend to be a little cheaper, which is why I'm going to start with it. If it can't keep up, then I'll consider a Ca reactor. But essentially, they both do the same thing, add Ca to your water.
As pointed out earlier, the kalk reactor is limited by your evaporation rate, which may or may not be an issue.
I would go with the Kalk reactor too. There are a few tricks that you can use to increase the Kalk levels if it becomes necessary (vinegar, adding fans to increase evaporation, etc) or you could also add a little extra calcium with a two-part solution periodically. The Kalk provides enough calcium for most reef tanks though IMHO.