Yellowing

Looks like light stress, and a phosphorus lockout. I would recommend to recalibrate your Ph meter and raise the lights up or dim their output.

Thanks for your replies. Really interesting. I use the plagron feeding schedule. I now give alga bloom and green sensation. I also add some epsom salts to my feeding water on weekly basis. Could that be tje cause? I also added some extra Ca in my soil at the beginning. PH should be ok. It's strange that these plants in air pots have this issue. It's my first grow with my new led and first grow in air pots. I never feed over the maximum recommended dose. Always a bit lower (less is more)

could be senescence, but i ssee you started to flush... this is likely the cause for any immediate and drastic nosedive.. your plants look much more lush in diary, if that is the same plant(s). late in bloom is when you see how balanced your feed truly was -- if not solely caused be flushing. Refer to a leaf symptom chart. you can see how the problems present themselves allow you to deduce possible causes. If you don't also know what you provide it becomes more of a guess than an educated guess. pH problems can cause any and all toxicities and deficiencies. Having a toxicity of certain molecules will cause a lockout several others even if they are present in acceptable concentrations in the substrate. Ruling out a pH swing is first thing you should do. Calculating the ppm of what you feed from gauranteed analysis labels can help decipher what is going on too. This is less helpful in a soil context, but can still help... especially by end of grow, because you are typically providing everything by the end, unless it is some super soil or similar context. So, i see potentially N-deficience because of how the yellowing is occuring -- bottom up and from tip of leaf in toward the stem. NOT interveinal or top-down.. that would be something else, potentially. Rust spots could be Ca or if the also have some interveinal chlorosis (paling between veins first before it progresses) it could be Mg deficiency. An Mg deficiency actually began 4-6 weeks ago but you don't see it until much later in the leaves. Knowing what you feed can help rule out things... e.g. if oyu know your pH is solid and you know you provide plenty of Mg, you can be pretty certain soemthign else is the root of the problem. Too much p or k is common in bloom due to marketing of "bloom boosters" to pot farmers... Too much p or k can lockout out mg/ca/fe et al... Too mcuh Ca, another marketing monster, can prevent uptake of magnesium and manganese... Again, this is late in bloom and you began to flush... the plant will fade in this context 100%. A fast fade is a clue in itself too. IT could fade so fast unless the substrate is right on that "edge" of providing enough to maintain growth relative to amuont of light provided and numerous other environmental factors that make up your context vs too little at which point plant fades quickly. The purple/red in some leaves is most likely temperature related (<68F at night?) or simply a trait of that plant. If you have a fall season, you should be familiar with changing colors of leaves. this is no different and same exact causes. Your pots are a potential issue if the plants been in those same pots for a very long time. A rootbound plant can have all sorts of nutrient uptake issues -- even if you provide enough of each necessary element for plant growth. You'll know better after you harvest. pull the plant out and obseve root zone.. is it a coiled mess of seemingly only roots at the bottom? That *might* be why but no guarantee. Fabric pots air-prine roots. they can still become rootbound, but it takes much longer. A minor adjustment to balance of nutes and overall concentration may do you good, but due to context of coinciding senescence and flushing, it's a smaller factor of what is going on at moment, i'd venture to guess. Week 13 in diary looks fairly solid. little tip burn, but nothing major 7 weeks deep into flower. You'll have to apply some deductive reasoning given your greater access to pertinent information. I'd guess only a small adjustment of what/how you feed is useful. most likely flushing is the cause of what you see now. Look into what sources of magnesium and calcium you provide. use some nutrient calculators.. Check my ppm table in any week of any recent diary. It is only meant as a ballpark. Ca/Mg/S can vary quite a bit based on tap water. mine is very hard, so you may need a bit more of any of those three than what i use. Figuring out what you add as a soil amendment is more tricky. i've never had to do that so i'm not well versed on how to do so. this may be a bit of trial and error -- do you want to solve potential issue through your soil or simply what you fertilize with? adjusting soil is much more work and time to figure out, but could result in less effort of fertilizing. (*check out "super soils") Whatever you do, in this case you definitely want small adjustments. it was healthy 7 weeks deep into bloom, so it can't be far off. it could be pot-related if it is rootbound, but even after inspecting roots, shouldn't be extremely confident without more data. More so if the plants are not exact clones... most plants are similar in needs, but there is variation, especially in robustness... they all generally like the same happy zone, but some get upset faster than others due to deviation.

Looks like a cal-mag issue perhaps, but lots of nutrient issues can cause that appearance so it's hard to say. Too much phosphorus, for example, can lock out cal-mag but is actually an issue with overfeeding. Same thing with wonky ph in hydro. Its tricky to diagnose under yellow spectrum light, if you can turn those off and get a photo under natural white light (or even the flash from your phone camera) it would be easier to judge. There is some necrosis of the leaf tips which can be a sign of over feeding, or issues with leaf transpiration. Feel free to send me a message if you want me to take another look, happy growing 👍🌱

Looks kinda like she’s overall hungry to me. I’d give a solid feeding, maybe 1.5 times what you normally are doing?