Octopus Tank Lighting

[Octopussie]

i currently have a 50g octopus tank setup. i cut a piece of plywood for the top and drilled holes in it for my canister filter lines and also cut a slit for my protien skimmer to fit in. i also constructed a surface skimmer box out of a breeder box for my canister (see in the pic below). i know how octopie have a need to escape, so i have to keep openings to the minimum. the only question i have is what type of lighting should i use?
can i set a light behind the tank facing upwards? octopuses are nocturnal so i would also like to set up some kind of night lighting.
http://i233.photobucket.com/albums/ee250/anthonyb989/Picture008.jpg

http://i233.photobucket.com/albums/ee250/anthonyb989/Picture007.jpg