Weird issues with LED lights / defficiency?

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Hello good people, I'm growing for 10+ years with no issues under HPS, I managed to go through the whole cycle of veg and bloom without losing a single leaf or having any sort of defficiencies, but it all changed as I recently switched to LED. Now I'm having very hard time to keep the girls healthy. Lights are only thing I changed. I'm also still running one tent under HPS (same strains, same mother) - no issues whatsoever.

I have a number of tents, same setup everywhere, in each tent I have
  • 32x 3l coco pots under 2x Lumatek ZEUS PRO 600W in 240x120cm tent
  • Clones - ICE and Mazhar
  • I'm running these lights at 50% for first few days and then going 100% all the time about 50cm from the tops
  • Using Canna Coco and Canna Aqua Veg+Flores+Rhizo+Cannazym
  • Also tried Advanced Nutriens - no changes in defficiencies
  • Using regular tap water with EC 0.4 pH 7
  • Regular IPM in veg - no insects
  • Otherwise I do not spray them with anything
  • RH is around 40-50% all the time, temps 26°C in daytime and around 20° in the night
  • Watering is done by flooding (EBB flow table), by hand in the beginning when they need it and 1x a day in with flood in full veg and flower,
  • I'm watering a bit more in veg and a bit less in bloom, but I never go close to wilting
  • I water 1 hour after lights switch on and no more that day, so they have time to dry up before next watering
  • My pH is 5.4-5.9 in veg and 6.0-6.3 in bloom, also I'm using 2 pH and EC meters for cross-checking values if one of them goes wrong
  • EC - tried heavier feeding in the last run (don't have pics) - 1.7 in veg and 2.3 EC in bloom - didn't end up very well, veg was a total disaster, lost more than 50% of leaves, but I switched them to 12/12 anyway and they kinda came back to life and went green
  • When I flushed few pots during this horrible run for testing my values in the pots I had EC over 4.5 and pH under 4 in my drain - not ok. In the end - yield was bit lower than I expected, but considering that girls looked like they went through nuclear explosion - it was ok, 1.6g/w
  • Lighter feeding is what I'm trying now (pics below) - 1.5 in veg and max 1.9 in bloom (this is week 4 in pics), but I'm still getting this weird defficiences, in much lower scale but I still don't know what is the reason
  • I'm also trying to add calmag for this run, seems that it helps a bit
  • I'm also noticing, that I have violet stems all the time which is a sign of early N deficiency, but it doesn't seem to change when I change EC at all..
  • Its very weird as some girls look perfectly ok and some look horrible.. same strain, same everything...

Thanks for any ideas

Ph 007

Ph 007

Haha this is me I went from hps using for about 10 years done led grow looked exactly like your I Alsobg as red woody sets looked like shit yellowing leaves and all sorts deddiaccanya drink slow, but I had slightly better yield then Hps even know the looked like shit the buds looked amazing.

Then I did 2 grows but I now upper my temps to 80-85max and smashes 5 a plant dry in soil my best do date.

Less give off no radiant heat so th3 leaves are colder then Hps even if your running the same temps as hps ,, cold temps causing defficientys ,

Try try running day 80-82f
and night 10 min less Then day

I also found I need calmag with led in soil, it yet soil hps I never needed calmag i didn't even know what it was before led lol.
You may not need calmag only i done 4/5 grows total with led so I need more testing with calmag or no calmag and the last 2 where my best by upping the temps to 80f+

You will notice they will drink faster like they would when you used his when you upp the temps to 80-82

I'm now back on hps now lead was head work, it better for a sealed room, and when hot weather I dim my Hps from 600 to 400 or 275 but I'm still testing 275 it's a little small my foot print , so if I dim my Hps to 400 I then dim my leds to 100w each so my total elector is still 600w
Ph 007

Ph 007

And them feed strengths seem very high like you said, specially for veg
Id stick to the feed e.c you always have with hps


hps I never needed calmag i didn't even know what it was before led lol.

Exactly, if someone knows about some resources behind this calmag with led thing, I'd be happy to read some science.

I also suspect some kind of fuckery from fertilizer companies, for example Canna afaik never made CalMag agent before and now they do. So either it came up as necessary suplement and its legit or they removed/decreased CalMag amounts from base nutrients so they can sell it to us separately. I really never had to deal with mono/micronutrients before this

Anyway, thanks a lot guis


"Sometimes magnesium deficiencies are reported when making the switch to LED’s. This is because magnesium is a central element in the production of chlorophyll. When we make the move to LED’s, a more chlorophyll targeted spectrum is part of the benefits. As well as overall higher photosynthetic activity. But in order to reap those benefits, we need to match the elemental requirements of the increased chlorophyll focused reactions taking place."

From pacific light concepts website


Take this with a pinch of salt, no pun intended.

I had similar issues on my first few LED grows. I grow in ProMix so our medium is a bit different. CalMag seemed to get me back on track but I personally hate buying the stuff.

What i wound up doing was add 1g per gallon of Epsom Salt to my salt fertilizer (I add disolved Epsom salt after my regular fertilizer is mixed). That took care of the Mg. Instead of using RO I started mixing 1/2 RO and 1/2 Tap and that took care of the Ca. Haven't had a problem since. I think it's just a matter of dialing in your nutrient schedule to the LEDs. You might want to get your tap water tested just to see exactly what's in it.

Also, I can't remember the last time i checked pH. =P
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