Red discolourations at the edges of the leaves

Cool temps (likely at night) / genetics. anything near or below 68F has the potential to bring out autumn/fall colors. This is about chemistry and not genetics. Same reason leaves turn color outside as temperatures drop. Some genetics are more predisposed to exotic coloration than others. Red petioles (leaf stems are different anatomy than "stems") are most likely caused by the LED if isolated to the top and where they are exposed to light while remaining green under the canopy. There's no way i've found to avoid that and i'm not alone in that respect. it's normal. Looks like you have a nitrogen deficiency creeping up the plant, so that would explain why it's slightly pale. the plant next to it might be getting a tad too much by comparison. Google image search a "marijuana leaf chart" the one stamped with jorge cervantes name is the one i prefer and has served well for years. This takes the guessing out of what you see, and also shows how many of the symptoms have more than 1 cause. You ened more information than just leaf symptoms. what you've done the last several weeks or even months matters. not everything happens quickly, sometimes a slight imbalance takes a very long time to become apparent. Don't start with believing that it has to be the last thing you've done. calcium deficiency is necrotic spots. Mg, a different element, has different symptoms (chlorosis with spots). ca and mg are not linked together, they dont' come together, it's just the name of 1 product that happens to contain both. think of them separately becuse they are.

The stems will be genetics,I have it.They're pretty pale so lacking nutrition.I guess the leaf damage will be the plant drawing the Phosphorus and some Potassium out of the leaves for the flower sets.The first 2wks along with 5 days 3wks beofre harvest needs extra P and K and will take it out of the leaves.Things liek Bud Ignitor and Flower Burst have extra p and k among other things and then you have the pk boosters that are mostly made to give in wks 4-6 to catch that 5 days window 3wks before harvest.Up your EC.

Calmag won't "fix" the leaves that already show that purple-ish red discoloration. It might halt/reverse the light green/dark green zebra striped leaves that I'm seeing on other leaves though. For that, I would use epsom salts since I'm not seeing anything resembling calcium deficiency in your pictures .... However, Aside from the signs of showing a small magnesium deficiency on some of the leaves, to me, the color pattern shows more "purple/red" than "rust" and suggests to me that your plants are showing the first signs of the approaching senescence and you're seeing the beginning of "fall like" color changes in your plants.

Es können mehrere Ursachen sein. Entweder Lichtstress oder was ich vermute eine Nährstoffblockade. Miss mal deinen runoff wie hoch der PH und EC wert ist. Wenn diese zu hoch sind dann giesse nur mit Wasser. Um zu sehen ob es am Licht liegt benutze eine App die Photone heißt mit deinem Handy kannst du die Licht Stärke messen.