Huhhhhh on the MB site did a fantastic build. This type of scrubber is the most powerful you can fit in a small space, because all of the light is strong and near to the screen:
SimonSKL on the MD site also did a nice build that lets you remove the screen while the water is still flowing:
And here is a video of the screen removal:
[ame=http://www.youtube.com/watch?v=_P0ZITI0h6o]YouTube - Scrubber design from SimonSKL on Marine Depot[/ame]