hello all... i have a 600w hps will that be enough for a room thats 6'8 by 6'8 by 6' tall i'll have mylar on the walls. or will i need a 1000w?
This may help you.
Choosing The Right Lighting System For Your Garden - Worm's Way
250w is not mentioned, but having used one I can tell you the area is less than 4-5 square feet.