If you have to change the water anyway (which you definitely do, at least once a week) why not just clean your gravel at the same time... kill two birds with one stone, so to speak. Cuz if you use this air thingy, you still have to do the water change, so you're not saving yourself any work at all. You're actually doubling your work. Sounds silly to me, wouldn't waste my time. Are you the one that just got a 250gal aquarium? If so, then what you need is a Python. Period. You'll wonder how you lived without it.