Do everything else as for the first variation. If the pressure in the upper hose is too high, place it in a piece of pipe (I used the pipe with the in...
I will show you how to make a very simple but effective venturi vacuum pump out of cheep laboratory material. You will need several minutes to make it. The principle of this pump is that when the water flows through the vertical tube, the vacuum is generated at the horizontal tube.This type of pump is widely used in chemistry labs for many purposes as filtrating under reduced pressure for example.
In this case I have used an 1.5 mL eppendorf tube and 3 pipette tips of 1 mL. You can use any sort of pipes as long as you follow the rule from the drawing (intro). To glue the parts I used a glue gun and to attach the pump to the faucet, I used the plastic hose that can fit to the pipette tips and a piece of a bicycle tube.
Cut one pipette tip at the place where it becomes to get narrower, about 3 cm from the top (the tip on the left), and cut the other one about 2 cm from the top. You should now have 2 pipette tips with different radii.
Cut the eppendorf tube about 1 cm from the bottom and drill a hole close to the other end as in the picture. You can cut of the cap. The dimensions don't have to be exact. Just make the parts so they can fit to each other. (See the further steps).
Cut the third pipette tip several millimeters from the top so it can come in the hole you made in the eppendorf tube but it shouldn't go deep into it.
Take the shorter pipette tip from the step 2 and push it into the eppendorfe tube from the bottom. It should end several millimeters under the hole you made. Put the pipette tip from the previous step into the hole and glue all the gaps with a glue gun.