Nutrient Burn?

Does this look like heavy nutrient burn to you?

It started from the very end tip of the leaf and now the margin of the leaf looks burned.
This is only visible to the upper leafs that get the most light, lower lead are healthy.

-Strain is White Widow from seeds, 2 phenotype are affected, 2 others are doing fine
-Pictures are from week 8, but right now its week 9
-Plants are in coco, feeding jacks 321 1h after lights come on until runoff, then a flash feed every 3h
-Nutrient Strength was 580ppm, i've just started reducing calcium nitrate in half so right now is about 430ppm

Overall the grow went great, i think its too late to do anything right now, but this started to appear some while ago, trying to avoid this on next grow, but not 100% sure it's burn since runoff is always +/- 100ppm from input

Thank for advices!

Forgot to add that i have a fungus gnat problem that was going out of control, could this been affecting the plants?

Situation is under control right now, i added a layer of sand over the coco, next run coco will be pasteurized prior to usage.

Coco loves to hang on to potassium...what you're seeing appears to be a potassium deficiency. What do you use for water and what ph?

Ya I also think that looks like potassium deficiency.. I see some red/purple stems too that could be a phosphorus deficiency as wel?

Potassium was my first thought but because i was seeing from top i concluded it was not the case.

Water is tap, never been analyzed but it's 80ppm, PH is around 5.8 - 6

Stems are green, petioles of the leaf are indeed purple but it doesn't bother me since i think its pretty common under LED Lightning

If u cut down on your nutes and its the end of this run maybe its using up all the nutes already in the plant and starting to kill off fan leaves. Just a though

URaDEADBEATdad said:

If u cut down on your nutes and its the end of this run maybe its using up all the nutes already in the plant and starting to kill off fan leaves. Just a though

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This started to appear before i cut nitrogen in half. Potassium and Phosphorous level are the same.

Had similar problems on my two last run with an other strain and GH Heads formula, it's the first time i use jacks 321, the grow went pretty good exept for the very last part compared to GH where i ran into all sort of problems, cant blame everything on nutes, im still learning a lot!

Glenkush said:

Potassium was my first thought but because i was seeing from top i concluded it was not the case.

Water is tap, never been analyzed but it's 80ppm, PH is around 5.8 - 6

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Ppm's are great, but when you say ph is 5.8-6..is that straight out of the tap?!, or after adding food and adjusting?

My tap comes out at 7.1, i ph down it to 5.8 -6.2. I start it low and fluctuate it during growth so the plant can get the certain metal that are more easliy consumed in the proper ph range. I add all my nutes then ph down. My ppm is about 520 on a 700 scale out of the facet. Im not sure what that equals in EC probably around .3 but thats just a guess. I like to hit about 1.6 EC during flowering which is about 1350 ppm but again im guessing. Ballpark anyway im sure some of these experts have exactly what it equals

Blitz35 said:

Ppm's are great, but when you say ph is 5.8-6..is that straight out of the tap?!, or after adding food and adjusting?

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water ph is about 7, when i add full strength nute ph goes down to 5.8. but right now im about 3/4 strength so i manually ph down to 5.8, ph slowly raise to 6-6.2 until reservoir need to be filled again.

Glenkush said:

water ph is about 7, when i add full strength nute ph goes down to 5.8. but right now im about 3/4 strength so i manually ph down to 5.8, ph slowly raise to 6-6.2 until reservoir need to be filled again.

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Are u using AN nutes i hear they automatically balance out to 5.8

IMO I still think it looks like potassium deficiency. Did you say that you intentionally fluctuate your ph to help your plants absorb the micronutrients? Interesting.

Sure do that way the plant gets all available nutes. Some nutes wont take at 5.8 and others wont take at 6.5 so its best to let your water hit the range i mentioned before.

URaDEADBEATdad said:

Are u using AN nutes i hear they automatically balance out to 5.8

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No i use a local brand that no one ever heard of, it's dry salts that i mix to get the exact same ratio as the jacks hydroponic 321 formula that some guys use over here.

This is not commercialized for cannabis but for vegetable grown in greenhouse so it's really cheap, for 200$ i got 15kg base mix, 25kg calcium nitrate, 25kg epsom and 25kg MKP
this will last me about 5 years and i will only run out of base mix which cost around 60$ and i'll good for another 5years with the rest of calnit, epsom. MKP will last me for arround 50years since i use about 0.2g/Gallon, quick calculation im good for 125 000Gallons of mixed nutriment

That's what's up, set for life lol