I have a CPR overflow with the Aqualifter pump. It stays connected and on 24/7. It automatically will start the syphon again if, for some reason, you lose syphon, so that's why it's good to have it on all the time. However, if you unplug the Aqualifter, the overflow will not lose syphon, so it will still work without it. But, if you unplug it, there's a chance that your main tank will overflow if something happens to the syphon. Like I said, it just starts it automatically if, for some reason, you lose syphon. And you don't have to suck on any tubes if you use the Aqualifter. That's always a plus.