I've been in the hobby long enough to see it come and go as a fad additive a couple times. It exsists as a product purely because of a misinterpreted scientific paper and a greedy aquarium supplement company. After that is was just copied by other supplement companies because it represented more easy sales and they could have the same elements that the other companies had.
Also, keep in mind that a couple of the authors that have promoted the use of strontium through the years also just happen to be owners of supplement companies.
There is zero scientific evidence that strontium supplementation is beneficial. There is evidence that it can be toxic at levels that would be fairly easy to get to if supplementing regularly.
Below is an excerpt from RHF and a link to an article written by him.
"Strontium may or may not be useful in coral reef aquaria, and it may or may not become depleted. Like magnesium, strontium becomes incorporated into calcium carbonate in place of a portion of the calcium ions. That incorporation happens to approximately the same extent whether a coral skeleton is being formed, or an abiotic (nonbiological) precipitate on a pump’s impeller. It is just a fact of life that strontium looks a lot like calcium, so it gets into places where calcium would otherwise be. Some aquarists have concluded that strontium may help corals to deposit their skeletons despite the absence of any evidence of this in the scientific literature, and of any direct experimental evidence (for or against) by hobbyists.
Some hobbyists do report positive effects of dosing strontium. Scientific evidence indicates that some organisms need strontium, albeit not the organisms that most reefkeepers maintain. Certain gastropods, cephalopods and radiolaria, for example, require strontium. There is, however, no clear evidence of any benefit of supplemental strontium in coral reef aquaria.
A few years back, when I tested my aquarium’s water for strontium (using a sophisticated lab machine), I found that in my reef aquarium, with no recent strontium additions, strontium was already elevated (15 ppm) above natural levels (8 ppm). By testing the Instant Ocean salt mix that I was using, I found that it, too, was elevated (15 ppm). I saw no evidence of depletion, at least not when performing my routine of changing 1% of the tank's water daily. I would not like to see the strontium level get any higher, because strontium is known to be toxic to some marine organisms at levels not too far above that. Consequently, adding a supplement without knowing the aquarium's current strontium level is not advisable.
Overall, water changes with a salt mix containing a suitable level of strontium may be the best way to keep strontium at appropriate levels, assuming it has any benefit at all. That requires no testing or worrying about dosages. For those who want to dose strontium, or who have very high calcification rates, which may deplete strontium faster than it can be replaced by water changes, I recommend testing to ensure that it does not get too high. My recommendation is to maintain strontium levels in reef aquaria in the range of 5-15 ppm. That level roughly spans the level in natural seawater of 8 ppm. I do not recommend that aquarists supplement strontium unless they have measured strontium and found it to be depleted below 5 ppm."
Aquarium Chemistry: Strontium and the Reef Aquarium — Advanced Aquarist | Aquarist Magazine and Blog
but I dose it every week but never test for it. Always heard from fellow reefers that it benefits zoas..and I love zoas..so far I have not seen any bad effects of dosing strontium but do remember someone saying it does play an important part also in the SPS growth and coloring up of corals.. Would like to know more..
