Can you get some shots in natural sunlight?
IMO To me it looks like you need a tad bit a cal/mag from those brown spots on your older leafs but for future when we say "tip" we mean the tip tip ^ <---, yours is on the "edge" of the leafs paired with the brown spots "Cal mag to me" . LEDs tend to make plants really eat up cal/mag so it's just something you have to watch under that light. I was at Full strength on my setup (dry cal-mag) at around week 3ish give or take (FOR MY GENETICS) but I do have a NL strain in there. Cal mag is cheap though if you dont already have a supplement or some people use Epsom salts and ph and Foliar Feed.
Hope we get this thing solved! Also posting a pic in the "infirmary" would help if no one else chimes in, lots of seasoned greenthumbs that lurk there wait to help
-The SpacePope

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