Maddog
★★★★★ Legendary Member
In the winter you're simply heating with electric heat when any lights are turned on.
Every bit of grow light gets "put to use" - either into growing veg or dissipating as heat wherever it lands off the plants.
I wouldn't sweat the cost of grow lights in the winter.
too cold to sweat in the winter . . .
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Unfortunately you cant really measure lumens with blurple lights, because as the saying goes "lumens are for humans", its basically a measurement of how the human eye PERCEIVES light, but because of the wavelength of the red/blue lights, it doesnt work at all with those. You can measure PAR (photosynthetic active radiation) but need a fairly expensive tool to do this.
unfortunately there is a conversion for lumens to watts