I have been using Dr. tims pearls for 2 years in a cad lights reactor. I hate the reactor because it clogs so easy and is a pita to clean. That being said, I love using bio pellets. Pros: way less glass cleaning, corals look great (might have nothing to do with the bio pellets). Cons: not many. It seems like my potassium levels drop when my reactor is working properly so I end up dosing more potassium when the reactor is behaving.