Have you measured your nitrates and phosphates? The biopellets themselves are just a food source for de-nitrifying bacteria but will do little for your phosphates. One key point to note that is many folks route the output from their BP reactor to their skimmer as the water coming from the BP reactor is very nutrient rich and can actually lead to algae growth in your DT. Most run GFO with BPs and if you'd like to learn more about BPs, I'd checkout this 2-part video:
[video]https://youtu.be/9UtgjkEg8EY[/video]
Enjoy and good luck.