Thanks eronjohnson. I thought it might be harmless but wasn't quite sure. Drip systems seem to be pretty popular and I'm sure they get plenty of algae on the exposed substrate.
As for sticking it outside, this is an experiment to see if I can have fresh tomatoes during the winter. I want to make a go with it inside under
lights. As you can see, it's doing quite well under the current ~6400 lumens right now. I'm planning on getting two two tube T8 shop fixtures within the next week or so and placing them vertically on either side. This will add an additional 11,000 lumens and distribute it more evenly over the whole plant. The whole mess comes to around $45.00 plus tax at Home Depot. Like I said before, I'm not happy with the price and availability of
bulbs for this specialty fixture I bought. I want to replace it anyway, so may as well start now, and almost doubling the lumens at less than half the cost, I can't not do it.