Natural sunlight will do it but could give you green water also. Plant fert will do it also just don't dose something, most likely NO3 and leave the lights on as long as you can. The longer you leave the lights on the morealage you will possibly get. 16 hours should do the trick but watch that your fish don't show signs of stress from it. Just don't forget to dose PO4 or you will be left with green spot algae and never get it off if you ever want to.
If you don't have plants, then just dose any type of fertilizer and that should get it started.
Don't expect live plant to grow though, the algae will quickly kill them.
I would also have some kind of algae crew in there because they will control it and almost landscape it for you preventing it from becoming a ssimple jungle of algae and strip the tnak of oxygen for the fish. Keep your circulation up and make sure to add a good airstone to the tank because the alage will strip the oxygen, especially at night.