I have a twelve gallon Nano Cube for about 12 weeks and yesterday I noticed no water flow. Took out the pump and the shaft on the propeller had broken in two due to RUST! If they are all made like this you better have a back-up pump. Lost the receipt so I put in a mini jet with 84-159 gallons per hour. Seemed to be a little strong so I have it turned almost all the way down. 25 dollar lesson.