I was chatting with one of the lfs guys. He is a real minimalist, doesnt even run skimmers on the tank, much less reactors and whatnot. Anyways he was asking me what kind of calcium in in natural seawater. I was like, duh, I don't know. He said Calcium Chloride (makes sense to me!) and then he asked what kind of calcium is used in kalkwasser, (again, duhh....and a blank stare from me) and he said calcium hydroxide (I think that's why he said), and he even mentioned another form of calcium that people typically dose (I can't remember). So anyways. Is there a discussion somewhere about the different ways we dose ca in our systems and the pros and cons of each? Thanks.