Need some help figuring this out

Just recently started having issues with this HSC raspberry parfait gal. She's five weeks into flower. Running dwc with GH Maxibloom per the feed chart. Using tap ph'd down to 5.5. No cal or mag since my tap has sufficient amounts of both. This just started a few days ago overnight. My pH had dropped to 4.2 and my ppm was 850. All of my upper sugar leaves look like this and crumble to the touch along the edges. Running 15 Samsung influx strips at 12 inches on an hlg480 dialed down to about 440. I corrected my pH back to 5.5 and lifted the lights to 18 inches yesterday. Any thoughts on this? Is she able to be saved?

pH crash+ dwc = roots

How do roots look?

Billy the Mountain said:

pH crash+ dwc = roots

How do roots look?

Click to expand...

The roots look just fine. I figured I'd raise the light and dial it down to quite a bit just to see if there was any chance of recovery. I've had various small issues from time to time, but everything I've grown from HSC has had similar issues happen.

A couple more pieces of info. The 3 other plants seem to be perfectly fine. 12.5 square foot tent and the 3 other plants are from @Useful Seeds and are thriving. Temps had been running around 86-88 with humidity around 40-45. Since dialing it down, the temps have dropped to around 80. I usually run everything with ambient temps around 86-88 since I'm using led.