its the temp of the cfl bulb. They will be different colors when you turn them on......one is a blueish color and the other is a yellow/orageish color

blue is best for vegging, and yellow is best for flowering
I however have not noticed a difference in the two when growing:twocents:
keeko Reviewed by keeko on . Need some Help please, lights and such... hi i have a lil set up going right now its actually two record crates lined with aluminum foil ontop of each other u kno with the open sides to eachother to make a bigger cavity for the plants anyways i have that with 2 pots in it and a 42w CFL thatputs out 150 my question is, is this enough for vegging? should i go get another 42 watter? they have been vegging for 11 days like this on 18/6 do u think i should get another bulb of a differ watt or the same and what type of size do i want for Rating: 5