Deficiency or over feeding?

[710slickxx]

Hey guys, got a couple plants that are acting wonky, was wondering if the problem could be id... heres #1
Coco/perlite 50/50
Feed @ 900 ppm
Cal mag with every feeding
Leaves curling up and leave tips turning yellow

 

[hotrodharley]

Leaves curling the edges from heat stress. How old are these?

 

[710slickxx]

Leaves curling the edges from heat stress. How old are these?

Right at 9 weeks. Its been 75-79 max in there the whole time

 

[hotrodharley]

Right at 9 weeks. Its been 75-79 max in there the whole time

They’re still exhibiting heat stress regardless.

 

[710slickxx]

They’re still exhibiting heat stress regardless.

Maybe it could be light stress?

 

[hotrodharley]

Is there air moving across these?

 

[InTheValley]

potassium deficiency, Flush and chop, they look done.

calcium shouldnt be used the final 4 weeks of flower, it just wants mag/potassium more then anything. At this stage, when calcium is in abundance and not used, it blocks potassium uptake.

 

[710slickxx]

Is there air moving across these?

A little bit, not as much as id like

 

[710slickxx]

potassium deficiency, Flush and chop, they look done.

calcium shouldnt be used the final 4 weeks of flower, it just wants mag/potassium more then anything. At this stage, when calcium is in abundance and not used, it blocks potassium uptake.

Not just yet, trics are still clear

 

[710slickxx]

2 more weeks lol

 

[Aussieaceae]

Not a big deal imo, looks fairly healthy to me.

Have you checked the ec of your waste recently? If it gets worse might be worth it.

Doubt it's potassium deficient. Would be plenty in your fertilizer, and coir fibre itself. Potassium can lock itself out though. So it is possible it's in excess, but i don't think it's worth pin pointing any specific nutrient problem at this stage. Just focus on ec.
FWIW, i've had top leaves looking like this under hps. Thought it was heat stress / low humidity. Turned out it was the ec in my coir, and with the combination of heat and low humidity, it dried my tops out.

 

[710slickxx]

Yeah i need to put up a better fan

 

[InTheValley]

 

[InTheValley]

it could also be the strain finishing up, mine do this too, they taco close to the bud, and that tells me i have 2 weeks left.