Most likely you have an imbalance of either calcium or magnesium and this could be most likely be related to ph and uptake issues.
Other than that it's just natural aging process.
Hey there, I thought I'd poke around and check out your diary on Amnesia Haze Auto from Barney's Farm. I grew this same strain and did well with it. Good luck and I'll continue to check in on your progress. Have fun!
Dope diary! Clawing can come from over watering as well, not sure if I seen you mention it in your notes. I had a lot of these same issues in my first tent grow but good luck come harvest! The dry trim and cure is gruelingggg
Congratulations on getting into growing Cannabis. Yeah you never wanna use testing strips. You can get cheap PH / PPM meter combos off of amazon. I invite you to come check out our tutorial series here on grow diaries as well in video form on our youtube page, Which you can find off of our main grow diaries profile. We cover the day to day step by step all the way from sprouting seed to harvesting, Drying, Curing & trimming. Come check us out I look forward to seeing you over there and hearing your feedback!