Ne Obliviscaris. Humidity Day 40-45%, Night 60-65% Internodes are very close together. was hitting 450umol at seedling level making it absorb more than it can use, reduced to 280-300umol @18 hours as expected vertical growth increased. During the 18 hours of daylight the first 9 is highly saturated in blue, 5000 kelvin, the 9 hours thereafter are closer to 3000 kelvin. Last 9 hours dosed 280nm. Height is too far to cause damage. UVB light is not detected by plants in the same way other wavelength/colours are. UV cannot be measured using umol as it doesn't drive photosynthesis. The plant has tiny little sensors that get set off to even little amounts, dimer salt bridges, the UV decays these salt bridges, which initiate response. You don't need large/long exposure doses for the plant to recognize UV is present. What's an enzyme? Think of it like a multiplier, you can add an enzyme to any particular biological process to vastly increase its proficiency at a particular process. Cannabis plants take blue/violet light and use it to create an enzyme called "photolayse". This allows the plant to repair UV damage done to the plant using a process called excision repair, this repairs the damage at a much much faster rate than it could by itself. Repairing 100% damage. The key is the plant needs time to build a reserve of the repair enzymes before using it. This is replicated in nature as, by midday UV levels peak, the generally cooler mornings allow lifetime to build up. The problem I encountered was dosing with 280nm lights on or 1 hour after the lights were on. Photomorphogenesis, the plant plans for the future of its growth, if the wavelength is not present during growth then how can it plan accordingly? The very presence of UV changes parameters with which the plant will grow, light itself dictates the growth pattern of the plant. Not only that it can dramatically alter the regular terpene profile of a strain in unexpected ways. Gran daddy purple grown using 280nm can triple already high terpene linalool. Linalool is terpene best known for lavender, largely responsible for its beautiful smell. Trouble sleeping you say? Having tried Durban poison from a dispensary and reading about its levels of tetrahydrocannabivarin. I've always wanted to taste the difference UV would make to such an already stand-out strain such as Durban.