Seachem has their "Reef Advantage Strontium" that come in powder form as well.
Seems as though they are all pretty much strontium chloride.
Have gone for long amounts of time without adding any to my tank as well as long times with it. I use the Salifert test to guage what my level is.
Like someone else noted, it is a relatively cheap additive so why not? I've spent way more on phytoplankton and oyster eggs to find no difference at all.
It is the test kit that is expensive and complicated.
All that said, I find that I have better results when I do add it to my tank. I do try to keep it to the lower side of the recomended (by Salifert) level.
Like anything else you add to your tank, it is never a sure thing that what you are adding is really the cause of your good results (or bad) or just a coincidence that was really caused by something else you are doing.
I do seem to have a major increase in PE at night whenever I do raise up my Strontium levels, pretty much right away. This is why I've always percieved it as a good thing. Could just be my imagination, but stuff just seems to do a little better with it.
