I agree with Loola, I've used nothing but CFLs so far haven't had any issues but I don't use any 6400k bulbs during the flowering. If you can replace all your CFLs with 2700k.Well it's been said that 6400k is for veg stage and 2700k is for flowering. I guess you should be using more 2700k. Replace the 6000+k bulbs.