I have pellets and they do work but it's a love hate relationship. Very little adjustability and I have had to start dosing nitrates because of an imbalance between phosphate and nitrate. The bacteria requires both phos and nit to process one or the other. My nitrates are undetectable but my phosphate is still there. I fought a cyano bloom because apparently cyano only need phos to survive. If you're good with paying attention to your tank and monitoring levels, biopellets are good IMO.