Question 1, Calcium

[Ruth]

I certainly don't profess to understand the whole chemistry thing that goes on in my tanks but I do know through trial and error and doing a whack of research what works for me and at what levels my tanks seems to do their best. I try to maintain my aquariums calcium between 420 and 440, my Mg. at 1300 to 1350 and my KH at 6.5 to 7.5. Salinity between 33 and 35ppt. I run a calcium reactor on my 2 large systems and I would highly reccommend running this piece of equipment on any larger system that you plan on keeping calcium demanding species in. I am going to try adding some magnesium granules to my reactor media next time I have to add some to see if this will eliminate the need to dose mg. On my 44g cube I do dose C-Balance 2 part solution but I find this a PITA to stay on top of and not have swings in levels. If I do find my calcium dropping (which has not happened since I brought the reactors on line) I have some Kent turbo calcium that I plan on using.
I agree with Bev that it is difficult to talk about Calcium without also discussing the balance of KH and Mg as they are all related and integral to each other.