i have been running these lights for about 6-7 months. i just got my wife a camera for her birthday so we haven't had a camera before for growth pics. i can tell you that while growth has been pretty good, and about on par with the t-5s i was running prioir. the real difference has been with color. i had a couple of pics of my tank before the kessils taken with an iphone and nothing up close just a couple of the whole tank. so not good for comparsions on growth, but after looking at those old pics man what a difference in color. the t-5s had my colors looking pastel, and now the colors are much more concentrated. i think another two will help with growth but the color i have gotten with these kessils is amazing.