Just did a water change and decided to try using a siphon hose in addition to the tub drain. Wow, was I surprised at how fast it emptied the tub! The only hose I had handy was from my wet/dry vac, so it was a pretty big diameter. I used the pump to start the siphon by putting the hose up to one of the larger jets and it really took off. I'm definately going to use this method from here on out. Now, if I could only think of a way to use the same idea to re-fill the tub!
