Can you please tell me what model and how much media are you currently using?
Usually biopellet reactors have to be introduced into the tank slowly. This means that you add only little amount of pellets at the time. Also, biopellet reactors can take up to 6 months before you start to see actual results. Remember that biopellet reactors provide the carbon for bacteria to feed on. The reactor does not provide the actual bacteria. So you have to allow the bacteria to catch up to the food provided. The carbon provides the food so that bacteria can thrive and as the bacteria grows, so will the consumption of the biopellets and also your nitrates and phosphates. It is all about reaching a balance between the bacteria, biopellets and bioload in your tank.