They say the Tunze can be used on and off, but you have to leave it off for an hour. It will also shorten the life of the pump....????? What does shorten mean? It last 4 years instead of 5? 9 years instead of 10? At that price if it only lasted 1 year that would be $14 a month. 2 years would be $7 a month, that is probably less than you spend on food.