Ok i have grown outdoors and know the sun gives 10,000 lumens per square foot. Now indoors is all new to me and everyone is always saying watts per square foot. which one is it. If i use my entire space for growing 6.5' x 5' with my 1000hps I will get 30.7 W/sq which is the min you need.... in Lumens i would get 1000hps = 140,000 so 4307lumen/sq well above the min 2000 and well above the optimal 3300. Can anybody explain this situation to me. thanks
Bare in mind the following : a. lumens are measured @ 1 foot distance from your bulb. b. lumens are how bright things appear to the human eye so it does not equal power. c. Watts/sq. foot is dictated by the power of your bulb and the shape of its reflector and the height of the light from the ground. Do you understand?
Wattage is a measure of electricity consumption. Lumens is a standardized measurement of the amount of light given off. Since different kinds of bulbs have different efficiencies at converting electricity into light, lumens is really the measurement you want to pay attention to. However, indoor lighting is sold and classified by the wattage it consumes as the standard comparison, with the lumens printed in smaller letters somewhere on the label. For HID lighting you can assume a fairly linear conversion of watts to lumens so therefore lighting standards often are quoted in watts per square foot, just as a convenience because we all know the wattage of our lights. But ultimately that is just supposed to be a shortcut way of reference the lumens.