I wondered about that switch. Seems like you could stand at the faucet with gravel tube in hand, turn on the water to fill the entire hose with water, carry the gravel tube end to the tank, set it in so the gravel tube is up to let any air out, and submerge it to start the syphon. I haven't bought the switch yet, or the tubing for that matter. I couldn't find the piece that connects to the faucet that switches the flow, so I picked up a cheap ($2) garden hose diverter (looks like a "Y"), the type that has little "ball valves" in them. The holes in the "ball" part looked too constricting so I drilled it out to the same size as the inside of the housing. Preliminary testing shows that it works. We'll see...