Gcarroll is correct. You really do need to understand the dynamics of biopellets before you start utilizing them. Like any measure in a tank, it can be very beneficial (or not). Lots of factors intertwine to get a tank optimized. Nutrient control is just one aspect.
Nitrates and phosphates can be controlled in many ways. Feeding, number and size of fish, substrates (and there are lots: rock, sand, ceramics and each has pros/cons), skimmer, pellets, water changes, algae, refugiums, gfo, carbon, all of these can and do play a role in nutrient control. Both too much or too little has its own list of issues. No easy, short solutions atleast not for me. The ecology in a tank shifts for a multitude of reasons sometimes slowly and sometimes overwhelmingly fast. It's trying and often frustrating to understand what's happening and responding accordingly
I don't utilize biopellets but I am not a naysayer. It's fun to have fat fish and pellets help in that regard. I don't think biopellets necessarily lead to the best color or healthiest coral but integrated into your reef keeping it may be beneficial. Of course if I knew more, my tank would be highlighted. I have my reef up and prospering for periods of time but unfortunately also suffer through some less prosperous times
So far I don't know of any panacea for guaranteeing a successful sps tank and I am pretty convinced pellets are not the panacea. I just keep on trying.