So at this moment I am using a four bulb t5 fixture on my 120 gallon tank, which is 48 in wide.  My plants are growing great and my rainbows look descent. All four bulbs are 6,700k.  Even though rainbows supposedly look best in lower K to mimic sunlight, I really miss the flashing that is much more visible with other lighting.  My lfs has a rainbow tank lit by only a LED fixture.  The ripple effect is cool, but it doesn't do much for the tank. I just don't think the strip is enough lighting. I went to another LFS yesterday and the had a smaller LED just as an accent to a normal light strip. When the bows past the LED they looked GORGEOUS! You could see all these colors that were not usually seen and they were flashing like crazy! So here is my thought. Online there is a strip for 119 that's 45 in. I'm thinking of buying it and just adding it to my tank, along with the other fixture. I'm scared of the extra algae it would produce. Is that a rational fear? Would they hurt my plant growth at all? I have also thought of only turning them on when I'm around or showing the tank off. Is that the better option?