Sick plants won't recover: Deficiency or burn? Flying bandit medical grow

[Highwayrob]

Title: Sick plants wont recover (deficiency or burn)/Flying bandit medical grow

Hey guys,
So I've recently acquired a medical license to grow. I have little experience as does the designated grower. We have a setup that's been constantly adjusted as we dial in the tents.
The plants were fine for the first couple weeks but started to show nutrient burn. We stopped feeding nutrients as the soil seemed to be loaded with them already. Flushed for several weeks and think we have the soil manageable.
The runoff of water tests at ph 6.9 (goes in no higher than 6.8 and we use a meter to test and balance our pH.
The ppm of the soil without anything added has runoff around 1200 ppm. After we leached the soil it brought it down to around 4oo ppm. Still 3 weeks later and the leaves show signs of what we've been treating as nutrient burn.
The tips turn white and the bottom leaves turn yellow and die. Tips are curled and some earlier leaves had dark veins and very pale green leaves.
I'm starting to think the soil had tons of the wrong nutrients and now giving it anything fails.
The next we think to try is lowering the pH a little more around 6 and hope the overall soil environment lowers to reduce possible nutrient lockout.

Should we flush still?
Should we give anything for a deficiency. Or shall we concentrate on pH still?
These were already set back schedule about a month as i dont want to send into flower until we have some healthy looking plants.
TO top things off we just got the LED light installed and setting it up burned a couple of the plants.
We were running a 400W metal hallide in a 4X8 tent. We have two blower fans with a carbon filter exhaust. Temps are within 22-25 degrees Celsius. humidity 50-75%.
We feed about once a week until water flows from the bottom of the grow bags.
I'll post a ton of pics from the early grow to the current stage so you can see the progression. (trying to upload to site now, timed out, trying again- doesn't process, shows old photos that failed first time, have to get to bed for work, will try tomorrow)

Would really appreciate any help. These are 10 plants, 5 each of flying bandit and sorry i forget the other strain. I may be able to ask the donor for the strain info again.

March
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April
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May
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[GoldenGoose]

Have you been feeding them since flushing them for weeks?
You said you water them about once a week, do you water them as soon as the soil dries out an inch deep, or are you just waterig them once a week regardless?

 

[GoldenGoose]

Hi by the way! I'm no expert by a long shot, but I had some troubles at the beginning that started recovering once I sussed out how they like the water n foo

 

[Highwayrob]

Update: Wow the stuff I've learned since that grow.
The issue with that grow was multiple. I can see the first images (flying bandit and c+ kush), the dark green waxy leaves with crows claws on tips, indicates a Nitorgen toxicity. From there the roots got burned and could not take up their required minerals, so no matter ho wmuch nutes we fed it couldn't uptake them)
If anyone else gets this before they transplant to a larger pot, try to remove half the leaves and half the roots. Repot in fresh soil and when watering, only water the outer edge to force the roots to grow into it. It will be slow at first but once it has fresh roots, it can uptake the minerals and recover properly).

We didn't have enough runoff (get about 10-15% runoff- this will grab excess salts), and fed too often and too much. The ppM were astronomically high as the bottle said to go to 1200, however that's for hydro, we were in soil. The roots rotted on one or two, the roots burned on the others.
The LED light was too close and doesn't work as well as the HPS/MH bulbs.
I must say the crop would've been a lot better had I known about "GROWZYME". It's microbes that eat the salt buildup on the roots and can turn around a grow in a week or two. Use when feeding, or watering if you have root burn. If you dont have root burn, just add to nutrient feeding. Water/feed/water/feed is the schedule I find works best. ppM's for soil never above 900. Potassium Silicate only with water in early Veg (only twice- for strong stems), top 2-3 times only after 3 nodes and try to grab 2-3 nodes and shove them deep when cloning)
As always, make sure your humidity and temps are spot on for the cycle. Veg especially likes that 60-80% RH around 25degrees Celsius.
and for the love your plants! PLEASE use fans!. Moving air will help a LOT to reduce chances of mould growth AND help the girls develop the strong trunks, which you will NEED if you've topped it 3-4 times (unless you like using a tomato cage or bamboo steaks )
note: tomatoe cages are easy but you're going to automatically prune your inner portions, causing a massive lollipop effect. I prefer to let them branch out so they all get their fair share of light. Its FINE if they sag perpendicular, as long as they ALL do it, then you can keep your canopy height even and lower your light if necessary.
I feel like this post went from "whats wrong with my nutes" to "go back and re-read all your information twice more" (which is hard with so much conflicting information.). yes every strain is different and if you want a VERY easy strain, find some Violator Kush. We kicked the crap out of it on a run while we were dialing in some new hardware, and they STILL flourished! Green Crack so far is my fav for taste though and soil over hydro, while might not produce the same frostyness and density of buds, absolutely tastes and smells heaps better! If you're in for quality and not quantity, and don't mind putting in the effort, go for soil instead of hyrdo.