I think I've figured out the parts that I need, and that the hoods are pre-drilled to allow fitment of a single lighting tube.
Problem I have is that while my tank is going to be 4 foot long, it's not going to be very deep or wide, the amount of wattage seems to depend on the length of the lighting tube and I'm concerned that I'll basically just have too much light! My fish are scared of the light even with 10W in total at the moment!
All I've seen of flouresent lamps are claims of "this is brighter than the others", whereas I'd like one which is dimmer?
135 litre (35 US gallons) 6 Black Widow Tetra; 3 Mollies; 3 Bronze Cory; 1 Pygmy Cory; 6 Gold Barbs
27 litre (7 US gallons) 6 Guppies.