Hmm after reading this thread, i read this web page, and he uses t5s on his cold water reefs.
http://www.oregonreef.com/sub_coldwater.htm
"Lighting
Since everything is non-photosynthetic, the lighting requirements are really just for the viewer’s pleasure. I employ a six bulb T5 fixture over each tank..…but, unless I’m photographing critters, I only use two lights from each fixture to illuminate the tanks for ten hours a day. An actinic/10K bulb combination is used in each fixture…..and bulbs are only replaced when they burn out."
i dont think you'd ahve to much light outside honestly - if anything just build a box around the tank, or something like that to get rid of it or bring it down a notch
not during winter/fall anyways