I agree with FireDancer7905 and kiddevo. could be the prime or didnt you say you got a new python for christmas as well? That could possibly be it. I have never done anything with my gravel vacs to clean them before use, but mine only ever remove dirty stuff and never put in clean stuff. That does bring me to an interesting point. To people that use pythons and similar devices, do you run water through them before adding water to the tank but after sucking out the dirty stuff? I would want to do a quick rinse out in between cleaning and filling just to make sure that there is nothing left in the hose somewhere.