Mid/top leaves bleaching, cloudy, light green, between veins

Hi,
I have 12 plants in coco, autopots with air domes. Running canna nutrients. 3rd week of flower. Ec 1.85, ph 5.9. they are in the 150x150 tent. Under 660w 6 bar style led kept 60 cm above the canopy. I kept it lower for a few days but the light level never exceeded 900 ppfd anywhere and the symptoms occur on leaves that get less than 600 ppfd. (the tent next to it has the same plants showing no signs where its 900 ppfd everywhere, but the plants are in coco drip) I started noticing some leaves getting a bit paler/cloudy litghter green. Starting from middle to the tip. Not the the ones on the very top, mostly second from the top. The bottom leaves seem fine. Not all plants are affected. What is strange its happening in the areas where the light intensity wasn't necessarily the highest. Never had this in this stage.

At the first glance looked like mg deficiency (but started on the far end) or light burn (but also on not so exposed leaves). But the fact it's far end half, points me to potassium deficiency more. What do You think?

Few days ago they were praying a bit (last pic) so maybe potassium deficiency with a little too much light?

Cheers everybody, happy growing.

Dont change anything it looks beautiful. It looks to me like the chlorophyll is maturing. Your plant looks healthy.

Cpappa27 said:

Dont change anything it looks beautiful. It looks to me like the chlorophyll is maturing. Your plant looks healthy.

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Thanks for the input. Maybe they are indeed filling in from lighter to darker green and tricking me. I will keep an eye on that.
I've waited a few days and I swear it seems it was getting a bit worse. For now I raised the lights 20 cm and wait.

Maybe even a come more calcium and magnesium. I doubt its the light, it doesnt look like light burn or bleaching to me.

Cpappa27 said:

Maybe even a come more calcium and magnesium. I doubt its the light, it doesnt look like light burn or bleaching to me.

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I think @Carppa27 is right.

Unfotunately they kept on getting worse and worse. I think it was a mix overfertilization ( even though it was relatively low EC), some kind of root problem and too high light intensity. They are still alive but its going to be very poor harvest and severely diminished quality.

Unfortunately I lost confidence in auto pots. It was 3rd grow in a row where I have some kind of a problem. Ever since I moved from 15l pots to 8.5l and started using airdromes. 15 l pots are needed because they have bigger buffer zone for the salts to build up. If you want convenience of an autopot just use 15l pots, no airdome, coco/perlite, coco/clay pebbles light feeding. Or biotabs or other slow release organic nutrients and run straight water from res. I am moving to drip irrigation for maximised harvest and more control. Will give auto pots another go some day. When I have more space and time for experiments.

bles said:

Unfotunately they kept on getting worse and worse. I think it was a mix overfertilization ( even though it was relatively low EC), some kind of root problem and too high light intensity. They are still alive but its going to be very poor harvest and severely diminished quality.

Unfortunately I lost confidence in auto pots. It was 3rd grow in a row where I have some kind of a problem. Ever since I moved from 15l pots to 8.5l and started using airdromes. 15 l pots are needed because they have bigger buffer zone for the salts to build up. If you want convenience of an autopot just use 15l pots, no airdome, coco/perlite, coco/clay pebbles light feeding. Or biotabs or other slow release organic nutrients and run straight water from res. I am moving to drip irrigation for maximised harvest and more control. Will give auto pots another go some day. When I have more space and time for experiments.

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1.85EC is not low.
You are supposed to run autopots low EC .

Probably the air domes drying out the rootzone and giving salt build up.

Personally I don't like them because you can have problems..
Just build a dtw system
The only single benefit of autopots is they are silent, your already running pumps elsewhere so cut your losses.

I'd flush them if there's a chance of getting something in return and you can physically do it without a flood