I can't give you a useful answer to your question, which I really think is, "do I have enough light to support SPS
?" However, I can tell you that lumens (brightness) are more important that watts (energy consumption). Wikipedia indicates that the European Union considers a standard 60W bulb to produce around 806 lumens though (take that with a grain of salt). I think what is most important is the PAR (photosynthetic active radiation) which is a measure of the energy put out by the light a photosynthetic plant or animal can actually use.