It wouldn't be hard to measure the effectiveness. The effectivenss of most GFOs is written right on the labels. To answer your question, pellet will adsorb only slightly more than the same
volume of granular, but that is because pellet is heavier. Weight-wise, they absorb about the same amount. I'm willing to bet that their regular GFOs are about equivalent to something like PuraLock (or is it PuraPhos?), which doesn't work nearly as good as Rowa.
The HC GFO
is cheaper than Rowa with equivalent (possibly a bit better) results. Plus you save on shipping because you don't need as much as the regular GFO.
Check this page of BRS's out:
http://www.bulkreefsupply.com/a9/Gra...icle_info.html