First time grower and poster.
My setup is pretty scrappy, but I've got 8 plants (5 an unknown strain (free seeds from website), 2 Northern Lights and 1 Super Silver Haze (purchased online)) all being fed by drip 3 times a day from one reservoir. All of them were doing fine for the past couple weeks until this morning when I checked in on them and one of the unknown strain plants had the dark greyish blotches as seen in the pic. The leaf texture is also very dry and brittle.
![Picture.jpg](/data/attachments/711/711494-4fb7a712dd549dffa773b7419f5af27f.jpg)
From my research it looks like a lack of phosphorous, but would this only affect one plant if all 8 are being fed by the same res?
I'm using the FloraGro, Micro, and Bloom nutes and I've yet to up the strength. I know the Ph fluctuates between 5.7 and 6.5 because up until now I've been using distilled white vinegar as a poor girl's ph down (getting some actual ph down tomorrow). I also know that the temp fluctuates really badly since it's an attic grow and outside temps can reach upwards of 100 degrees (there's only so much fans and a window ac unit can do in an un-insulated garage attic >_<) But would either the ph flux or the temp flux cause a symptom like this?
Any help would be greatly appreciated. I wanted to make sure it was a phosphorous deficiency before I tried to correct the wrong problem.
Edit - Forgot to mention I'm growing in Grodan rockwool cubes (3x3x4).
My setup is pretty scrappy, but I've got 8 plants (5 an unknown strain (free seeds from website), 2 Northern Lights and 1 Super Silver Haze (purchased online)) all being fed by drip 3 times a day from one reservoir. All of them were doing fine for the past couple weeks until this morning when I checked in on them and one of the unknown strain plants had the dark greyish blotches as seen in the pic. The leaf texture is also very dry and brittle.
![Picture.jpg](/data/attachments/711/711494-4fb7a712dd549dffa773b7419f5af27f.jpg)
From my research it looks like a lack of phosphorous, but would this only affect one plant if all 8 are being fed by the same res?
I'm using the FloraGro, Micro, and Bloom nutes and I've yet to up the strength. I know the Ph fluctuates between 5.7 and 6.5 because up until now I've been using distilled white vinegar as a poor girl's ph down (getting some actual ph down tomorrow). I also know that the temp fluctuates really badly since it's an attic grow and outside temps can reach upwards of 100 degrees (there's only so much fans and a window ac unit can do in an un-insulated garage attic >_<) But would either the ph flux or the temp flux cause a symptom like this?
Any help would be greatly appreciated. I wanted to make sure it was a phosphorous deficiency before I tried to correct the wrong problem.
Edit - Forgot to mention I'm growing in Grodan rockwool cubes (3x3x4).