Looking dark green there. When do you cut-back on nitrogen? It's getting pretty deep into flowering, so you might want to think about restricting the nitrogen, or flushing it out of the pot.
Doesn't look like major ph issue, but I see a few leaves that make me mention it.

Likely best to fill-out the troubleshooting form.

From seeds or clones? All the same strain? Have you grown this strain without incident before...?
If clones, how long had they been rooted before switching to 12/12, and how tall were they when you switched?
Rusty Trichome Reviewed by Rusty Trichome on . Nutrient Lock ? Hi guys, having a problem with my grow....:( always involves fucking nutrients aswell !! hate them, may go organic but anyway...last 3.5 weeks my girls havent been growing much at all...so i thought it was my temps which were around 18.C but i sorted that out and now they run at about 21.3.C with my new heater...so a gave them a week an half since then and still they hadnt grown so i thought ah they dont have enough nutes so started giving them full strength feed...still nothing has really Rating: 5