PPFD is harder to measure without the proper equipment but your LED light should have a max PPFD rating, they should even have a chart on their website that gives you the output specs of the light. 900 PPFD is usually good, if you’re going any higher than that you need to start adding co2.
I agree with Potassium deficiency and possible spider mites, you should trim one damaged spotty leave and check the backside with a loupe or scope, you cannot see them true eye …
@Randomtask is spot on.
Leds get sold these days and advised just like HID lights, completly wrong thinking.
HID lights radiate IR heat and burn of more moist on canopy level.
LED lights have minimal radiation (or even none) and need a warmer growing temperature.
If the combo with the RH is completly of balance, the VPD is that bad the plants are on PAUSE = energy wasted.
You need a simple RH and TEMP logger to have this data.
A 600 watt led light, fully open … wrong thinking.
You need to measure the PFD output of the led to control that output.
All of my led lights from HLG have ‘never’ been on full power.
When you plant in your chosen medium, the leds needs to be on 250 - 300 PFD for a few days to let them get use to this tremendous light power.
Towards start of flower you need to up the PFD towards 600 - 900 PFD.
At start of 12-12 there needs to be a dropback in PFD power, -200 PFD is a decent target.
Towards week 5 again you go towards 900 PFD (1000 is possible with CO2 but all specs need to be on point, the priority is VPD)
Towards the end of the flower, again you need to drop back the PFD with 200.
HID light grow ops, use lower EC levels. Because of this moist burning IR.
Because the plant engine run allot of water they also take allot of nutrients.
In LED ops, this is where it differs. The burnoff of heat radiation is not there so the ec levels need to be 25% higher, minimal.
The plants i see from you pictures. It starts with the VPD error … and there is some light stress going on.
There is a Mg shortage, because the plants do not uptake enough nutrients overal, also to few micro’s.
As long you not get in control of the VPD and PFD, no matter what nutrients you use, how much, … the problems will stay.
K shortage is tricky, add more and you will block other elements.
Start with the basic climate and light power and stabilise first.
Dont forget leaf surface temp! Its lower under leds causing a need for a higher ambient temp to hit the proper lst. A simple laser thermometer helps a lot there.
Those are long leaf plants. I know what you might think. Long leaf plants to me take less watering. You could be over watering. Touching your plants with your hands will cause problems sometimes. Smoking tobacco or blunts. You drop your ph for the p and k. Your grow looks great. I run my lights a little on the light side. Low and no fresh air or moving will make them lazy looking. Sometimes plants get tired. I run 11 on and 13 off. I’ll cut them off sometimes. Good Growing. Just talking.
Can I ask why your shooting for such a low pH range for soil? 5.8 to 6.2 is lower especially if aiming for 6. You should be shooting for 6.2-6.5 with 6.4 really being the sweet spot… For as many people jumping in about deficiency but no one questioned the low pH? Classic example of lockout or partial lock out…
Of course he is falling off on calcium and magnesium, look at the chart and pH range he’s targeting, doubt he is getting good uptake of phosphorus either…
100% agree. Especially when feeding bottled nutrients like canna! But soil does have a pree good buffering capacity. I never ph my feeds of megacrop in soil. When i do its like 7.5 or something. Works just fine.
Is does but the original post says he is between 5.8-6.2 and watering in at 6, I don’t care how much of a buffer that soil has, u keep throwing 6(more acidity) at it and it’s not gonna magically jump up to 6.4 where he’s gonna pick up those nutrients everyone is saying he’s lacking 🤷 I see a simple fix here…but that’s just me
