you will notice a difference in yield . ok what you do . use those 2700k bulbs right up until you start your flush then put those 6500 k bulbs back in or better buy some of those 10000k purple or blue depends on the manufacture . brings out the crystals . I know t5 lighting . I have used it in the past when all my hps lights were stuffed full of plants . changing the bulbs last 2 weeks . makes a major difference in the crystals . with t5 . with in 4 or 5 days you may notice the difference in appearance .