Take some ibuprofen, and get used to the headache! Kalwasser is another form of calcium. Use can use kalwasser to replace water lost from evap and the kalwasser helps to keep the calcium at an appropriate level. I'm not an expert on kalwasser cause I never used it. Instead of kalwasser to keep calcium levels up, you can use, you guessed it, calcium. Alkalinity, without giving you another headache, is the carbonate part of the chemical equation. Some products include other chemicals as well, but alkalinity is very important along with calcium. Never add the two at the same time. Basically, Calcium plus carbonate equals calcium carbonate, or the coral skeleton. Now you see why the two are important!? The two need to be monitored and balanced out. Too much of one will deplete the other and so on. If the corals don't have the proper amount of each, they won't thrive. I hope I didn't confuse you or tell you anything incorrectly. You will hear pros and cons for Calcium and kalwasser. Good luck!