What kind of deficiency is this

[darkgrower]

My plants started having yellow tips on their top leaves, new growth, I am wondering what would this be? They are in their 7th week since seed (3rd week of flower).
Could it be CalMag deficiency or nutrient burn or something completely else? I lifted the lights and they are around 50cm from the canopy now.
View attachment 1772312View attachment 1772313

 

[DreamingHigh]

Looks like nutrient burn. You might have found your max feed strength

 

[BII]

Now you need to decide to continue to feed the same, pushing the limit, or be more conservative and cut back. I'd cut back just a little.

But if not already, you should be switching to bloom base nutrients. So you'll essentially have to start over with new nutes that may act differently.

 

[sc0rpi000]

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[GasPlease]

Im late to the party but thats light burn imo. Turn down your lights.

 

[Dab]

Potassium probably from too much nitrogen but it can be a lot worse don’t change much they look fine really

 

[BII]

Im late to the party but thats light burn imo. Turn down your lights.

Even if it is light bleaching, with the effect seen on only a few of the very top leaves, much like a little bit of browning on leaf tips shows you're pushing towards the upper limits, I'd not change the lighting intensity. But if it gets worse, raise or turn down the light(s), or train/lower (LST or HST) the top-most stems.