I had a 306 I used for @ a year, it worked fine the whole time. Set it on a shelf for a while and when I brought it out to use on a temporary tank for several months it was difficult to get started after every cleaning and finally quit altogether. Tried rebuilding the head with new impeller and gaskets but that was a waste of money, didn't want to spend more for a new pump. Not a satisfactory life span for that much money in my opinion but maybe others have had better luck.