[StirCrazy]

Originally Posted by Bartman

In any article I've read (eg. http://www.advancedaquarist.com/2005/12/aafeature1 ) the Ca for NSW is generally referred to as 410 - 420 ppm. Evolution being what it is, why would we shoot for anything outside this range?

because the average Ca in NSW is 400 . it varies a little in various parts of the world. I think reefers have inflated the numbers over the years thinking it is better. so if we look at the average we could easily guess that maybe we should be looking for 380 to 420. but there is also something else we should be looking at, Mg? nope it won't cause a problem or difference in Ca unless it is low (and that isn't from some book ) but Alk, Alk will allow your Ca to either go above normal, hold it at normal or let it dip below normal depending on its concentration. personally I don't know of any reef tanks that are perfectly balanced. I used to go for the higher Ca thinking well if 400 is good 450 must be better but found it wasn't over the years. I have found the chemistry that work the best for me is a Ca of about 380 and a Alk of about 13. now this is just my findings others might find different levels, but I think the "well if 400 is good 450 must be better" attitude has been creeping levels up for years.

Steve