I don't know enough to comment, really, and probably shouldn't - but does that plant look stretchy to you (or is it just me)? I'm on Experimental Plants No. 2, and am using a couple of fluoro tubes in a 4-foot fixture along with a couple of spiral CFS for side light. It's not my ideal lighting situation, but then I didn't have to find a couple hundred bucks to spend on an HID, either. When I get more money, I will be using HID. In the meantime, I use what I can afford - and this go round, the plants are looking decent. Mine look a little less stretched out than yours does, if in fact it *does* look stretched.
Good luck - and do share your carbon-filter making secrets with us if you care to do so as I, too, am curious as to how you constructed the filter.