<a href=showthread.php?s=&postid=10554646#post10554646 target=_blank>Originally posted</a> by spamin76
Ok - something to keep in mind about strontium...
It is very similar to calcium in reactivity, thus that is why testing for it is so long and convoluted... you have to make sure you get all the calcium up before you can get an accurate reading on the strontium.
Your water changes should be replenishing your calcium and strontium. If you don't have calcium problems, you probably don't have strontium problems as well.
Speaking as someone who knows a thing or two about biochemistry, most organisms require magnesium or calcium for many of their enzymes to operate... strontium is not a cofactor for any enzyme I know of in either eukaryotic or prokaryotic organisms... so in terms of biosynthesis or respiration there really isn't any evidence I have ever come across that says strontium is important for corals to live(or at least anymore important than calcium). If you know of any let me know the enzyme or pathway and I will look it up. There are some situations in which an enzyme will use strontium... but only in place of calcium.
If it isn't used as a cofactor the only other thing an organism would use it for is for skeletal growth. Now there is definitely evidence that calciferous corals have strontium in their skeletons, but quite frankly the presence of this element and the importance of this element are completely overshadowed by calcium(in this case calcium carbonate). Doing water changes honestly should be more than sufficient in maintaining levels unless you have lots of calciferous critters.
If you are coming across creatures that appear to have stunted growth and there is no other explanation than "it could be due to a lack of strontium" then you might consider dosing some. If this isn't the case though, I have never come across any compelling evidence to add strontium. In all likelihood, the strontium in your tank is being consumed not because it is a vital nutrient, but rather it is so similar to calcium chemically that it just gets sucked in in place of calcium.
The most likely places to find strontium are skeletal features, calcified shells, and calcified spicules(some soft corals, some sponges). Now strontium is larger than calcium, so it's incorporation into a skeletal semi-crystalline matrix would definitely change the dimensions... but again there isn't any evidence to suggest higher or lower levels are better or worse... more than likely you would just see subtle differences in density of some skeletal elements.
Edit...
I did find some studies where marine organisms were grown in a total lack of strontium... in a total absence these creatures had slightly distorted skeletal elements, but were perfectly healthy and able to live normal lives. This again is in the total absence of strontium, which is not the case in your tank.