How many of you use the "Python" type gravel vacuums, that hook to the faucet? What do you think about them? Does the faucet have to run the whole time, or just to start the siphon? If it works like a siphon, what happens if the tank is lower than the sink? And how do you dechlorinate the new water? I just hate hauling buckets, and in the winter my flower beds just don't drain that well to start with, and I run out of places to dump the water.