: Here's a link to a video of the pump in action.

: http://www.flickr.com/photos/willn2/6062820255/in/photostream

: 1.5 gallons per minute or about 6 liters.

I wanted to do this as well, but ended up putting a rule 500 cut into the minicell foam seat I made. It is out of the way hard to see and works great. I used Gnarlydogs info and the instructions from the company that coppied his setup and came up with a lithium opperated unit. The only hard thing to find is the reed switch large enough to switch the pump on, I found a 5amp reed on ebay for a few dollars.
The pump clears the water out in less than a minute.
You can download almost complete instructions to build one on that company's site that coppied Gnarleydog.
Good day.