It's my understanding that people use sodium HID lights for their algae based sumps because it works. You'd probably need to confirm that though.
Another thing you will need: A TS that big would be a huge pain to clean manually. You might consider something like a leather splitter design. A couple of rollers with the screen running around them in a large conveyor belt like setup. Put a sharp blade over one roller on the vertical face. As you turn the rollers and the belt passes under the blade you hair cut the turf and the cut-off falls off the vertical face into a hopper ready for disposal. You could even set it up so the belt is in continuous motion. Running it's full length every few days or a week. This would allow a very small motor to provide continual harvest.