Hps...400 or 600????

I currently have some white widow skunk females in a box 5'L X 3'W X 5.5'H....using flourescent currently but not gettin enough light....I am going to purchase a digital hps but a little concerned with heat..is ther a large diff between 400 and 600? I have 2 100 cfm fans currently for ventilation and a stationary fan inside...i can also ventilate the hood if needed...I am located in southern ohio and my box is outdoors in my barn..Will the lights offset the occasional 20 degree nights or will winter be out of the question?? Any advice would be appreciated ..just dont want to get the 400 and realize should have went with the 600...Thanks

For your application since you are using a grow box, I would go for the 400 watt one. Less heat being generated in your limited space also less enrgy consumption. In regards to your temperature fluctuation issues I could not answer for I live in northern calif.

Hey rwood... you should figure about 50 wats per sq ft for growing.. a little more or less wont hurt... a 400 is ok for what your doing, but if you intend to enlarge in the future go 600... the amount of heat you will gain or lose depends on your enviroment .. insulated bldg. etc. you should think about your digital ballest purcahse.. core & coil standard ballests give off more heat and are a lot cheaper...if you can vent off the heat in summer mo. or move the ballest out side id go standard ... sounds like your on your way... good luck

if you've got the box full of plants, you probably want the 600 to get to 40 watts per square ft. you're going to have to get stronger fans for the warmer months. not likely to be able to grow in the winter without insulation an a 24 hr heat source although the light will help.

In your shoes i'll use 600w with cool tube

think its possible to vent in the summer and use the lights to get the temp up in the winter, i could have the lights on at night to fight the cold and off in the day when the temp raises??? What is the lowest the temp can get and still be productive?

rwoodcock said:

think its possible to vent in the summer and use the lights to get the temp up in the winter, i could have the lights on at night to fight the cold and off in the day when the temp raises??? What is the lowest the temp can get and still be productive?

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i just see no way to both ventilate and heat this box without adding supplemental heat. even if the light was enough to warm the box when on, you are going to kill your plants during the day - and i've lived in so ohio. even a small electrical space heater would probably do the trick if you're careful with your venting