Filtration / ULNS

I've set up an algae scrubber today. Its gravity fed from my refigium via a few drill holes. I have lit it with 2 x energy saving light bulbs which use 20watts each, but give off 100watts of light (apparently). the water flows over an old under gravel filter grid with the upstand bits cut off , which sits flat on a sheet of glass. The grid is just to give the algae something to grip on to. It will also be able to be removed to clean off excess algae (if it works). Its just an experiment at...