These are two pictures of an inexpensive way to set up a vortex water trap and get good results. I think starting out like this is the way to go because it helped me to better understand the principals I was reading about. Any way if you mess up 2 liter bottles are easy to replace. The hardest thing about using gravity without water pressure like the other traps is that you have to balance the water draining out to be less the the water coming in.

You only need some:
* Aquarium Tubing - I used a vinyl straw that came with a plastic racing cup
* Some plastic bottles
* Duct tape
* Waterproof glue / epoxy
* Magnets - I have 40 right now and will add more soon
The Magnets are from Lowes, though Radio Shacks are the same quality and cost less.
I used a soldering iron to poke holes in the bottles and the caps

The bottles are supported by the top half of another bottle cup open allowing the water to drain without slowing it down.

Both of the straws skim from the top.

Let me know what you think: