The 65k is better for veg and the 27k is better for flowering,it wont hurt the plant to use different kelvins,just worry about the lumens,remember ther is 10,000 lumens in a square foot,i use 3 different kelvin temps 27k 42k 65k, i have 6-65 watt,8-26 watt and 4-42watt in 4 foot squared space.