I spent just under $400 total per light including a $95 Phillips bulb. The 3000k refers to kelvins. Heat production is virtually nill. May heat room up 5-7° tops with the 3 of em. Had lights 12" off canopy for penetration with 0 light burn on any leaves, did however raise them to 18" and maxed out to the ceiling now. Maintain humidity under 45 and temp under 80°, phenominal resin production and smelling like cat piss now, but flowers are smelling oh so fruity. Have Nirvana Master Kush and Chem91 and Golden Goat. M.K. and Chem are in Day 29. My first time growing anything. Using House-Garden COCO nutes, drip clean, bud xxl, shooting powder.