If you have enough LR to handle the biological filtration, you won't need to add any other type of bio filtration. I think adding a fluidized bed might increase nitrate levels as well. Do you have a protein skimmer? That's really the only extra filtration you would want assuming you have at least 1.5lbs of LR per gal .
Life is not measured by the number of breaths we take, but by the moments that take our breath away.