Quote Originally Posted by Hataman
Douglas1, I think you're on to something here. I have a 180W Blackstar veg and a 240W Blackstar bloom. The 180W veg light is an animal, and grows plants like nobody's business. I've now placed 3 plants under the 240W bloom light--going in, all of them were super healthy and rapidly growing--and almost instantly their growth rate dropped way, way off. Within a day or so, all 3 started showing these symptoms:

Attachment 283155.

This appears to be a sulfur deficiency. Although sulfur deficiency made no sense to me--I changed nothing except lights--I went ahead and applied garden sulfur and Epsom salt, but to no avail. The symptoms persisted.

I too have been fruitlessly looking around for light bleaching pics. Even though the symptoms of your plant look different than mine, in view of your experiences with your 240W Blackstars, the only thing that makes sense to me is light bleaching/photo toxicity. My 3 plants were placed 16" under the 240W Blackstar. One was in a 5-gal DWC tank, the other two were in 100% perlite hempy buckets. Not knowing what I was facing, I kept the DWC plant under the 240W Blackstar for nearly 3 weeks, and in that time it flat-out died. The second plant (the one shown in the picture above) was under the 240W light for 72 hours before I moved it back under the 180W veg light. The appearance of sulfur deficiency persisted, however, the plant has now slowly resumed growth. The third plant was under the 240W light for 24 hours before it too began showing the same symptoms. I've now moved it 30" under the light, and we'll see how that goes. I'm keeping my fingers crossed because 30" is all the headroom I've got, and I'm down to my last healthy plant.

My 3 experiences combined with your experiences have proven to me that 16" under the 240W Blackstar bloom light is just way too intense. This is surprising because, compared to the 180W veg light, it doesn't look all that strong. When I was trying to decide between it and the 180W Blackstar, I went to the Lighthouse Hydro web site for help. Both lights have 2'x3' coverage, and all the web site says is the 240W light is for those seeking a more intense light. Being a tyro, I figured who doesn't want a more intense light? If I had to do it over again, though, I'd go with the 180W bloom light. Mine is just a tiny, hobbyist, experimental, one-bloom-plant-at-a-time type operation, and the 180W bloomer probably would have suited me perfectly.
It is the light! my plant showed very similar symptoms to yours, but got much worse as time progressed because, not only did I think it was nute burn from too rich soil or something, and so did not fix the light issue until the girls were pretty much torched.. but my plants were also very small when I introduced them to two 240's flowering angled in on either side, and the 240veg over head.. needless to say, 350watts or so of true led consumption.. was a little overkill for the youngsters.

what has helped me now, was switching them all over to coco/pearlite mix, so I can get them nutrients quickly, and I know for certain that its not the soil burning them. and mixing up a foliar feed with micronutes, rhizotonic for the roots, and nitrogen.. I also turned off the two flower panels and put the veg about a foot and a half up from the plants. while the ones in pots are recovering slowly, the two in hydro are going full bore..

It's good to know someone else has had this problem, though its a good problem to have really


weezard, like I said, they had not been fed at all. I considered the soil being too rich, but the coco plants and the hydro girls all showed the same symptoms until I changed the lights. now the hydro plants have shot out new leaves, and the coco ones are slowly recovering. I planted a new seed though a week or so ago, and it's already outgrown the potted ones.. so something has changed for the better I think.