Leaves Light Brown

I have just this second watered her before taking photo. I water her half a litre every 2-3 days. I was under the impression PH didn’t mean much in soil but I use a mineral water that is PH 6.5 and high magnesium and calcium content, I use cal mag and Biobizz nutes. (Minimal amount as I burnt my OG Kush last time being too eager) Also I have noticed she isn’t growing from the node above the cotyledons it’s like it’s stuck or does it happen gradually?

Looks pretty wet bro, are you over watering the little guy?

Looks like a Magnesium deficency . Too light green for Phosporous and too burn for nutrient excess. Hope to help ✌️🏽

you are having ph issues, check your ph and you should also flush until your run offf is at a 6.0 ph. if you get the ph issue under control now you will have less problems later. if you do not get the ph in check your leave will be funky and die off as well as turn brown. it is an easy fix. also do you have drain holes in your plastic container just so the extra water drains out? other wise pick up some kelp and feed the plant every other feed. your young plant will recover, once you see thee plant recovering you should cut off any leaves that look like this so your plant will have healthy happy growth and not waste energy on leaves that are defected hope this makes sense and helps