Early stage magnesium deficency?

that's good you got your PH in check and even when feeding 1/2 the strength of recommended it can still cause to much of something sometimes. Just from looking I still think it can use less N and its good to remember autos like to feed less then photoperiods do. It could also be that your soil has to much N in it as well then added on top of the other nutrients is stacking. I would look into watering a bit less as that's what I am seeing from your leaves pointing downwards. it would also not be a bad idea to try and raise the lights a bit to see if it helps a bit. air pots have excellent drainage but soil can compact so its just a guess at this point. your temps look on point. Good Luck!

To me, drooping clawing leaves could be sign of too much water. Some nutrient disssolve easier than another. And I also had magenesium issue. So, I add a spoon of Epsom salt to a gallon of water and molasses to feed plant root once a week. I don't worry about pH. Most fertilizers are useful in wide range of pH. Two in particulars are troublesome. Iron is better at lower pH. More over, iron is an imobile nutrient. Feeding iron to soil won't hel[ much. Then, the easiest way for me is to spray iron sulfate to leaves every couple of weeks until flowering. Another difficult nutrient is molydinum. Plants do not need much. So I found seaweed with molydinum content and spray those to my plant during veg as well. But I spray sea weed on different day than iron. I try to be as organic as I can. And I feed my plants mainly with earth worm casting, molasses, seaweed, and compost tea. However, I do add Epsom salt and Iron Sulfate salt to help with defieciencies. I live in a "developing country" and get my fertilizer mostly straight from smaller farms at good cost. This may not be the case for most people.

So I've done a more comprehensive check of my pH to make sure everything is in order, the water I'm feeding her is 6.9, soil is 6.5 and run off is 6.8. I've been feeding only water for about 2 weeks now.... The only other thing I can think of is how it has got colder recently, doesn't make a huge amount of sense though cos it's still 24 degrees in the tent

I know it looks like N toxicity but I only fed them twice with grow nutes, and that was at half the recommended dosage. Although it was a pre-fertilized substrate I washed it out before planting so I really can't see how it's N toxic 😞 I also noticed that overnight she perked up and all leaves were pointing towards the light but then this afternoon she's wilting again. Really not sure whats going on with her

Hey Growmie, You've got a few issues but not a magnesium deficiency. I seen you ph was 7.0 last week which is not good, but I see you have it back to 6.5 but you have watering issues along with the light being too close try raising it from 15.75 inches away from the canopy to about 20 or 24 inches away from the canopy.

It looks like light stress. Plus you are still struggling with water issues.

No, its first heavy signs of nitrogen toxicity. That could lead from ph swings if watered while pot was still moist, to magnesium lockouts. When second happens, while trying to correct - people get all other things. 3-4 plain watering without food for her and she should bounce back.