A couple of tests that work very well for this are the salifert
alk and calcium tests. You can get 'em from darin at captivereefs for example. They are very nice tests to use. While you are at it you could grab some stuff to raise
alk and
ca individually like seachem's reef builder (raises carbonate alkalinity) seachem reef calcium (raises calcium)
And you could also get a
PH test too. These 3 things are very good basic tests to help you maintain good
alk and
ca levels and once you spend a little time twiddling with it you will find that it is pleasantly easy to do. For example I found that I had high
alk in one of my tanks and I gradually brought it right into spec with just adding seachem reef advantage calcium.
The benefits are nice, like fast corraline and coral growth and water stability.
Steve - S had a nice article that he linked about understanding these levels that was very helpful to me. I will go scrounge around and look for it.
If ou did indeed have a calcium precipitation, the tests will probably tell you that you have very low alkalinity (it may havey crashed after the precip) which is hard on the critters. You might be best off doing just waterchanges to get things back to reasonable levels before you start hitting it with supplements.
On that note, regular waterchanges are essential for a healthy tank and will also help to prevent things like this unless your salt mix is way out of whack right out of the bucket. This is another reason why it is nice to have those test kits so you are not running blind.
Hope this helps a little
