IMO, a UV is not needed in most tanks. It CANNOT prevent or cure an Ich outbreak because the lifecycle of the Ich parasite includes a stage where the cycts are on the substrate/rocks, and even if it was just a free swimming organism, as mentioned above, UV can only kill what passes through it. Spend your $$$ on something better!
I prefer my carbon and GFO in seperate reactors because they tend to need changed at different intervals, and work best with different flow rates.