tried both sizes ,,,both the double-duckbill rotators,,,they were ok for the money,,,,,the one for the larger size RIO did not work as well as it should. both tended to lock up early on,,,and if they lasted long enuf,,,,WORE OUT !!! they need to redesign them,,,,something about rotating pieces of plastic wearing on each other,,, not to mention, they were REAL distracting while running in the tank,,you eyes went to them instead of the inhab's of the tank. everyone that saw my tank , asked about the RIO rotator b4 what was in the tank.....gave them a honest try(had bought 3,,,would give them a thumbs down though
