600 watts of floro. wont hurt the seedlings but thats just a lot of extra lighting. I would say about half that and make sure they are compact floros. or cool white. You can ask any growing shop to point you in the right direction and they will let you know what works. Just tell them you are looking for 300 watts of compact floros made for veg groth stage(dont tell them what there going to be used for) You will need an hps sooer or later (at least 400 watts) to flower that many plants. you can get hps in a low emishion ballest so it doesnt burn up the extra electricty. If you are really worried about the electricty then rig up a 240volt outlet and get a 240volt ballest to burn half the electricty. If you decide to use the compact floros, make sure you keep them at least 1 foot away from the plants so they dont burn. The compact floros tend to get hotter than the cool white. Hope this helps. If you wanna talk to me personally about any Q's you might have, e-mail me at [email protected] .Peace.