Easy. Both priming and emptying. It's a secret, but I will share it
Take a vinyl air hose, and shove it up all the way where the bend starts. Then carefully suck out all the air, until <gag> the first splash of water hits your taste buds. Then pinch the hose and pull it out. Bingo!
(the outlet doesn't need to be primed, doh!)
To empty it (so you can replace the dirty acrylic non-lily pipe with a brand new one) you do the same, but blow instead of suck.
