This particular product doesn't seem to be any of the above.
http://www.brightwellaquatics.com/products/phosphatr.php
This product appears to be a GFO polymer resin from what we can tell.
See this thread:
http://www.reefcentral.com/forums/showthread.php?t=1268855&highlight=gfo+resin
This is a statement that Randy made about these type of products:
"What I'm saying is that I've not seen any reason to think it will work, but it might. I'm skeptical, but would be happy to be shown otherwise. I've also not seen anyone known to us post even anecdotal evidence that it works.
FWIW, "works" may mean different things to different people. If it bound lots of phosphate at 2 ppm, and none at 0.1 ppm, is that effective? For some folks yes, for others, no. The usual problem with such organic polymer resins is that they have high capacity for phosphate, but poor binding strength, so bind fairly little are very low phosphate concentrations (unlike GFO, which is the opposite: low capacity but high binding strength).
The applications are a bit different, but I've tried some of the best phosphate binding resins from other industries (like my sevelamer) in reef aquarium water, and it did nothing for phosphate. They are typically best (way better than GFO) for binding a lot of phosphate when there are less competing ions (like chloride and sulfate) and higher concentrations of phosphate (like 500 ppm). That's the situation where my product works (in the human GI tract).
That said, I do not know the chemical makeup of that particular resin. I could design, and have done so, very strongly binding organic polymer resins, but I wouldn't expect them to be available at a reasonable price for this application.
If anyone tries it, please let us know how it works out."