How hot does it get in your grow area? I have always thought it was cause of my high heat temps in my room for 5/h cause of my co2 set up , but never changed it to see ....but fat buds every time...if your plants aint turning a very noticable yello color...and the tips ant dieing and the new growth looks good ....its all good , some leaves on the lower part of the plant will wither and die in the 12/12 cycle though , need stored energy to flower cuts off resorces it no longer needs .....you know ..." use it or lose it "...lol...dont mind me ... <has a buddy that grows shrooms also.... tripping hard core...WoooHooo..been peaking for a hour so far ....lol....any way ...lol..curl is ok man...peace