[EdKruzel]

Adding purple up, aragamilk, Kalkwasser or any other calcium supplement is a necessary addition unless you do large weekly water changes with a quality synthetic salt. In a tank with coralline, corals and/or clams the calcium is used to sustain and build upon and therefore the most used or quickest used chemical in saltwater aquariums. Using a supplement or calcium reactor is the easiest way to maintain the proper levels, but a test should be completed on a regular basis to know how much to add.

Natural SW has an average of 420-460ppm of Ca, but can be a bit higher in a reef tank. Now tanks above 500ppm can be as bad if worse than tanks with too little calcium. If the water is super saturated, then the calcium based organism cannot absorb what is needed. If there is too little calcium it is like us eating less than a snack and trying to do a hard days work.