Well ill b honest....but don't laugh!! Lol
I was shocked at the prices wen I went light hunting, and eventually went to the Chinese mall which is lyk 10km from me and bought a 30wat flood light!!
But since I'm new to live plants, I thought "Wat the hell, I'll try it" lol
And it seems to b working as my java ferns are growing new shoots on the leaves so it's basically a trial and error kinda thing for me...