It's an idea that I had worked on, but with the new home that we are living in any holes that are cut into the house (dog doors - vents etc) void the energy savings guarantee, go figure on a solar tube of all things.
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I did a fair amount of reseach on these and they can work for a reef tank. There's lots of people who have had good growth and color results. search -- for solartubes and you'll find several memebers who have them installed, lots of into...Jim