Well, after a bit more poking around, I just wrote off to the folks at the Atlantic UV website (BTW they have a sizeable number of trademarks per their privacy policy page) asking for their suggestions, Included the notion of sealing one of their cold cathode lamps in a tube and dropping it in my res.
Interesting pix of your unit. Is the bulb actually in contact with the water, or is there a surrounding tube that you left out of the pix? Assuming you have normal sized hands
it looks to me like the tubes are around an inch and a half, and the base is about 2" Might make it a challenge to fit into a 1.5" pipe... However I'm not totally married to that size, so I could possibly have a length of bigger pipe down the bottom, though it will be a real nightmare of adapters... (I even have a big hunk of 4" left over from another project, though I'd hate to stuff something that big in my case.)
Gooserider