Cob Height over canopy / Burning plants

This will be my first experience with led growing and am having a few issues and wanted to get some suggestions from other experienced led growers. I burned the crap out of my girls by having to much light over them, now i have to recommended 25 watts per square foot at about 22" over the canopy and am still seeing a little burning here and there. i have had some issues with this strain under 1000hps the same symptoms just not as bad as with led. I think this plant is more light sensitive than some others strains i have. The mothers are under 2x 5k cobs at 700ma and this mother is burning a little in the veg room as well and i have never had an issue with t5's in there. Everyone is in fox farms soil and ph is 6.5, ro water with calmag and ferts every second watering. Sorry i didnt want to post this in plant problems because i wanted the led guys to look at it and see what they think, thanks for any input.

doesn't look like light bleaching, which I've seen once under HID and once with LED

but there are much more experienced eyes here

Looks like poor plant health from deficiencies which under quality LED will get worse than under HPS. Bleaching is white, I got a little once from getting my CXA3070 to close.

I get that too sometimes. Certain ladies are more sensitive than others. It usually happens when I switch them from a relatively dim vegging area to a relatively bright flowering area. But no worries, they will push through it and still give you a bomb yield

What a great optimistic reply!

thanks for the replies. It does seem to happen when i switch to the flower room, they are looking much better after raising the lights up. That may be a factor as well captain, they were in smaller pots in my veg for 2 to 3 weeks after planting from clone, and as soon as i put them in the flower room i repot to 5 gallon containers. just wanted a few trained eyes, i have not really run into many problems in my garden for the most part. thanks again

Looks pretty sweet to me. Is that a Blumat line?

Keep a close eye on them,a slight def under HPS can turn into a major one under quality LED. You should find you have to bump up your ppm's,some plants turn into mag whores too.

Its titan controls co2 line, again thanks for the replies.

I'm inches away, as little as 2-3" and no bleaching at all (3070 @ .7a). Had some ongoing battles with mg deficiency though (which, as mentioned, looks exactly like what you have there j5... not at all that bad in your case). You may find the light too much for younger plants.. ? which I'm thinking was a problem with slow, unhappy early growth but they look fine at your stage in the pic..

Seem to have battled it all along with this AK.
It needs some help right through flowering, hmmm.. maybe partly responsible for the slow start,
anyhow, no real harm done:

Tazbud said:

Seem to have battled it all along with this AK.
It needs some help right through flowering, hmmm.. maybe partly responsible for the slow start,
anyhow, no real harm done:

View attachment 3318833

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Its a cal/mag problem. when using cobs you have to HUGELY increase your cal/mag intake.

the key indicator to look for is the middle vein of the fan leaves, you can see the problem in your 1st pic and also the ak

the middle vein needs to stay white, throughout veg and early flowering, yours are red

this will cause problems, your ak, will not bulk

the level of cal/mag will vary for each strain, but large doses of cal/mag under cobs seem to be needed

n/m

Thanks for the info on the leaf stems unknown, what would you call greatly increased? i am using ro water and use the recommended 5ml per gallon, should i push that to 7.5? i dont want to over do it. again thanks for the info.

My tap is only around 50-60ppm, that ak has had either epsom or 1/2 to full strength calmag once a week since mid-veg (more epsom than calmag lately). It's a bit larfy this time, probably from a spider mite episode where I forgot to lower the light for a week.. but at this stage the def is under control, seems to get better with time (maybe a coco base thing as well..). My soil is on it's second and third cycle but very similar results to the first round (cal should be fine, mg def or perhaps reaching toxicity of something else??)
Anyhow, iv'e not had light burn with cobs yet, all good, merry Xmas!

I hate to say it, and I could be wrong......but get out your loop and look for root aphids.

"I’ve also seen geniuses on forums like rollitup.org who recommend grinding up onions and garlic, combining it with neem, cinammon, and other crap, and drenching the roots with it"

Lol:

http://bigbudsmag.com/stop-root-aphids-from-harming-your-marijuana-plants/

"I won’t be so cruel as to name the specific national soil brands that are known to contain root aphids, thrips, and other pests. Ask your hydroponics store or other marijuana growers and you’ll find out"

Mine isn't a root aphid drama, i but maybe you are right 10.30 it did pass my mind in the first run as they didn't respond quickly at all.. but then (i) dont buy soil and had it in a newer mix- like mine with puffy leaves (maybe a tad over-watered with the drench and water treatments?) and a bit of inter-vein chlorosis here and there (I even had it on new leaves at one stage) j5's look otherwise reasonably rigorous..?? (i'll be checking it out though when I pull her up)

Maybe try a garlic /neem /cinnamon & other crap drench tehee.. can't hurt
FoxFarms?

Anyone else feel Ca and Mg are used more with LED? It initially strikes me as odd, any theories as to why?