I have been using BRS biopellets for about 6 months since I took down a colls type nitrate reactor. I used about half of the recommended amount.
http://www.bulkreefsupply.com/store/products/carbon-and-gfo/biopellets/brs-bio-pellets.html
http://www.bulkreefsupply.com/store/products/carbon-and-gfo/biopellets/brs-bio-pellets.html