There is nothing wrong with biowheels. It's working the way it was designed for, and it is used extensively in aquculture. But none of my Penquins have biowheel running, because I only use them for mechanical and don't need additonal biological. I prefer greater water movement in my tank than to use up the energy to drive the biowheels. Besides, there is maintenance issue with biowheels like splashing, slime built up, and stopping. I will use biowheels only if I keep messy fish in sterile bare glass tanks. Penquin is very effective in mechanical that my water is crystal clear within 10 min after feeding. But I have to change filter pads as frequently as twice a week, which is a positive, not a negative, because left over food and waste are removed as quickly as they are produced.