Yes, from what others say, there are algae that can live in complete darkness.
I'm no biologist, but I would think some of them can live on that nice warm water and nutrient rich tube linings.
As far as the UV goes.. I would say this.. if you can afford the $70 dollars for a UV clarifier, spend twice that and get some Fluorinert,
http://www.hamptonresearch.com/hrproducts/2797.html....
It's a 3M product, use it instead of water, it's dielectric and I would bet nothing can be live in it.
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