dont find what it is exactly

hi there, leaves on my plants started to curl up or down and have brown spot on edges? my pot is 1.5Gallon and it is autocheese from canuk seeds. its in DAy38 from germination and the problems started this week?... i was using dutch science nutrients as 100% organic for veg stage. after a week of flowers i used only water and i wanted to start flowering nutrients this week. the plant is at 18'' from my little grow light wich is viparspectra XS1500 at 60% dimmed. my soil is perlite/worm casting/ peat moss. I water with 6.5ph. rune off around the same ph.what can cause that?

My guess is a bit of nute burn. Nute burn starts at top of plant like that, whereas nute deficiency starts towards the bottom of the plant. Least that's how i learned it.

hi, I tried to water it last 7 days and it seems to have not change the problem. look at the pictures below. The big fan leaves still have the problem. I hope ill be able to harvest before it reaches the buds sites. My PH seems to be ok. Maybe too many nitrogen? I will only water until it seems to be ok. but if you guys got any insights that can help ill gladly take them. thanks

Your plants are potassium deficient. Continue to only water will only make it worse. The damaged leaves will never recover and will always look like that.

so i need to start giving them nutes. using botanicare pure blend pro flower will help right?