I run my carbon dioxide 24 hours a day 7 days a week, and I maintain about 40 to 50 ppm. dKh in my tank is 3, it's a 55 gallon hi tech. in my fixture I run 2 54w 6700k, one blue and one purple (54w each). Both are marine bulbs. I have not had any issues with growth or algae.
Imho, its all...