This took much longer than I thought, but I finished my EX 70 based scrubber. It has two 3W LED's on each side that I can light separately. At the moment, only one side is functional as the bioload on the 55 gallon where it's installed consists of only 3 cories and one Threadfin Squeaker.
Here are some views of the scrubber.
I used the stock half of the filter cartridge holder as a framework to locate the growth surface in the filter and allow for removal for cleaning. The gravel was the only white product that I could find in the area and is courser than I would have liked, but oh well.
Now it's time to sit back for awhile and see how it works out.
Jeff