Gravel Vac That Hooks To Faucet

[Elrohirthehasty]

So I need a gravel vac that hooks up to my faucet.  I have a 10 g and a 29 g tank.  I have always just carried buckets of water.  However, I am not at home for long periods of time and someone else takes care of my tanks.  They don't like doing the bucket thing.  A new gravel vac that hooks up to the faucet costs $50.  I looked at it and said to myself, "this is maaaaybe 7 dollars in components".  Am I right to think that these suckers work by the venturi effect?  In order to drain the tank you hook it up and turn on the water?

 

[eaglesaquarium]

Yup, that's how it works.
 
I just use a hose hooked to my faucet.  Fill the hose with water from the faucet, then disconnect it from the faucet and you have instant suction (assuming the tank is higher than the sink... if not, you can just run the other end of the hose into the garden, via a door or window.)  Then reattach to faucet to fill tank.
 
Cost me about $25, including the hose (50 foot hose to allow me to water my outdoor plants from the tank).