I have 2 ML biowheel 350's. One is a much older unit. It runs like a beast. I never have any issues with. THe Bio-Wheels seldom stop turning and it is very quiet. How ever the new modle that I have used to give me issues every time I cleaned it. The impeller would not start right away. I would have to tap it to make it start, and it would take for ever it seamed like to prime. The water flow would start off good, but after a week of running the flow would be half of what it started off at. I have this one in a box in the closet now. I have an ac110 and an ac70. i now longer use the 110 I got a new Fx5 to replace it. How ever the 70 I have has been running for ever. I know I have had this filter for 10 years or more. I have not had any issues out of it. The impeller still works great the motor runs great, and the water flow could not be better. If I were to buy another HOB filter I would deffinitly buy AuaClear.