Have some issues with this 6 week old plant. There are some weird rust spots on the 2nd node fan leaves, not my first time growing so thought I would ask you guys for advice. Pictures below and details of setup below. Room: Humidity 65% -75% Temp 79 - 86 54 plants 3 strains under 3 1K Metal Halides They are in 2 gallon pots, all about 2-3 feet tall In CannaCoco Coco Ro Water PH 5.8-6.0 General Hydro Micro 6.5 ML and Bloom 9ML per gallon 1 ML super thrive for 32 gallons 1.5 Calmag Plus per gallon Ppm is anywhere from 710 - 790 Light 20 inches from top Lights on 20/4 Watered daily Only on about 3 plants, and it's only on the strain Blue Mystic. Also quick question, I have a yellowing problem from the bottom up, the smaller leaves are green, but bigger are all turning yellow and dieing, I cut most off, increased N because thought was nitrogen but still a issue. I'm assuming it's the light though because since they are so big and in trying to finish my flowering setup, lower leaves aren't getting too much light.
That's light bleaching...as far as the discoloration on the leaves higher on the plant. You've had that mh light too close to your plants. MH is pretty darn strong, so make sure you have it far enough away. I think the rust spots are a boron deficiency from using RO water. It's perfectly fine to use water straight from the tap and there are also micronutrients (like boron) in tap water that are necessary for the good health of your plant. Treatment plants stopped using chlorine...that will evaporate out of the water, and now use chloramine. Chloramine doesn't evaporate and there isn't enough of it in normal tap water to damage your plants. I've been using it straight from the tap and pH adjusted for years now with excellent results. I'm pretty sure if you'll stop using that RO water and start using regular tap water, the boron deficiency and rust spots will go away. You have WAY too many plants going to flower off under 3 1000 watt lights. Cramming a whole bunch of plants together doesn't increase your yield. You can always harvest more from one plant that has received optimum conditions than you can from throwing a bunch into a room thinking you'll get more. I flower with 1000 watt lights (hps) and the most I flower under one lamp is 4 or 5 plants max. You just don't get the coverage from the light to sufficiently finish out the plants when you have them crowded in that way. So when it comes time to flower these plants, I would be very conscious of how many I put under each light. Good luck! TWW