Browning leaf edges

I don't have an extractor fan either... all I have is a clip fan. What I do to "control" the heat and humidity is to unzip the tent partially. If it's heat I want to control, I unzip the top portion of the tent flap... and I may open up some of the top ports as well. If it's humidity I need to control, I unzip the bottom portion of the tent flap and go up about half way to the top... I'll also open up the lower ports and the screened "windows" at the bottom, again as necessary. I've even been known to unzip the entire tent flap and open all the ports... You've got to play around with it to figure out what's best. Autoflowers don't give two hoots about "light loss." But your problem here has nothing to do with either heat or humidity issues... it's a potassium deficiency which additional PK will be more than welcome to her. Make sure the pH is balanced and proper (in soil, between 6.0 and 6.3 but in coco it should be between 5.5 and 6.2). Good luck...