You are a little short on the light and a little hot but it will work just not best. Without CO2 you want to keep the temp below 80F if you can and you really want 32 watts or better per sq. ft. or better and you have about 28. If you add the lights your temp will rise, so can you vent the heat? Oops, missed the no vent post. What about using small chunks (less then 1/4 lb.) of dry ice in a small foam chest with the top open in front of the circulation fan. That would cool the closet and raise the CO2. The major posible problem is CO2 levels over 2500 ppm are harmful to you and your plants. You really need to find a way to vent the closet.:smokin: