The tips of the upper leaves (as shown in Picture ...

Hi @braziliangardner! You over-fed your plant, burnt tips are usually the first signs of a Nitrogen toxicity. You should not be giving such doses of BioGrow once the flowering stage has started. Now as an emergency move, I would flush the medium with plain pH'd water (~6.2) for a few days until the runoff comes almost clear/clean. I think you're following a bad feeding schedule, I've been using Biobizz for a while and had great results following this schedule: http://www.420magazine.com/gallery/data/500/Untitled124.png. This one has been made for autoflowering strains, and has been tested and approved by me and other growers around here. If you manage to get rid of this toxicity, try to stick to this schedule next, you should not have any deficiency nor toxicity using it. Hope this will help, keep us up-to-date and happy growing 👊

Hello ! So that king of tips can be caused by heat or a light too close from the top of the plants but with you setep and your temperatures I would not bet on one of those 2 issues. The burnt tips can reveal you that your plant is under a nutrient excess , the dark green colour is a sign of a nitrogene excess and could lead to a salt buildup and a nitrogene toxicity. What fertilizer are you using and in which amount ? I can see that you'r using a Ph meter but no Ec/ppm meter which is a important tool to know exactly what nutrients amount you give to your ladies. My thaught is that a flush can help to wash the exess of nutrients in your soil , if the water runoff is brown then it's alright your flush is a succes , flush until the renoff become clear ( for a soil reboot ) or until the brown color become less brown. And get a ec meter as soon as possible. I hope it will help you 😁👍