I have a 5x5 that I have done great with just 3 viparspectra 600. With the occasional tip burn on the plant closest to the light at 22 inches but still minor. Recently upgraded to 1 hlg 260 xl rspec quantum board. At same time was gifted a 4 light cree cxb3590 3500k 200 watts. Same color as the QB without the deep red. Both at 30 inches above the canopy. And evenly spaced from each wall. So I did away completely with the blurple. Now pulling 470 watts in a 5x5. IMHO that's not enough. However all 4 girls are tip burnt and leaves folding up. Very obvious light or heat stress. Room temp is 78-81 and 38-49 RH during the day and a steady 72 at night with 45-50 RH. Any ideas?
Mine are 8 inches from 288QBs (in flower) and no burn. That seems super strange. I went all of veg with a 300W QB as close as 16 inches with no trouble. Did you switch mid grow? Maybe they're just not used to that intensity. Sent from my SM-G975U using Tapatalk
Some of today's LEDs are just too powerful. I too can get burn at 30 inches, and my tents are only around 75 F, so I know it's not heat stress. I had to dim them. Dimming makes sense, because the newest LEDs only require about 28 watts per sq ft. I was giving the plants 40 watts per sq ft, and they don't like it. Also, increasing light distance has a much smaller effect on lowering intensity than most people think. The inverse square law applies to point sources of light, not to our grow lights. I also have 5 (60 watt) COBs in a different tent, and I dare not get them closer than 30 inches. Because many people are able to use shorter light distances, this must be grow method dependent.
Thanks for the response. A bit of back story...2 were switched midway 1 hermed from the switch...had to be I've ran it many times with no issues. Over night noticed all hairs red so trashed all but one that looks like only half was pollinated so decided to keep it. I then put 2 in that were vegged under vipar 600 (250 watts) at 24" Now 23 days on 12/12 shoved in opposite corners as far from the light I can get them. Sorry for the book I am just at a loss I am still a newbie but have a year-and-a-half under my belt with many successful Harvest and about every problem you can think of but can't figure this one out?
I fan the hell out of my space. In a 4x4, I have two fans on the floor blowing up through the canopy, one oscillating on the floor, three clipped in the corners and one on the ceiling, plus my exhaust fan...maybe overkill, but my plants are currently closer than I'd like, but doing fine. Maybe you just gotta up the airflow. Sent from my SM-G975U using Tapatalk
I'm glad to hear you say that because everybody else I have talked to said I am nuts I hate the thought of dimming 470 watts in the 5x5 but it's really my only option from here
They look great how old? But I have two oscillating fans on the wall one on the floor and one above the lights plus my exhaust fan but I will try it I have many extras I just thought I would get wind burn. Thanks.
Middle of week 4 of flower. Almost 2 months from seed. Just keep em all on low and look for stuff that's doing more than dancing lightly. Adjust them until they're not bending stems. I like to put my hands around the canopy and look for hot, stagnant areas and adjust my fans to resolve. Sent from my SM-G975U using Tapatalk