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.
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.
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).
I've been holding off on upping my nute strength for fear of nute burn, but I guess I need to feed them a little more >_< Along with Ph down, I'll add an EC or ppm meter to my list of things to buy. Anyone have any suggestions for what kind of meter to get?