Can't speak to the other but I've been using bio pellets for about two months now, in an aquamaxx reactor. The outlet of the reactor feeds the inlet to the skimmer pump. Skimmer produces about 2x what it used to and nitrates are under control.
I've used NOPOX, it took less then a week at half the dose to go from 20 nitrates to 0. Since then, I've been using less then half of recommended dose every other day, works for me.