HYDRO HELP with brown spots

[Desil14]

I have two autos a day away from 12 weeks from seed. They’re in a bubbleponics hydro setup from GWE. Temperatures have been good since summer is ending staying in the 70-80 range. Humidity has been less than 50%. I use the GH nutes, calimagic, and hydroguard. I follow the schedule posted on GWE. The brown spots are only on one plant and seem to be spreading. Any ideas on what It may be?

[gbauto]

Overall, nothing major.
Looks like she has a slight Ca deficiency, so you may need to up the concentration.

[Desil14]

I had bought some Cali magic since my other plant was showing calcium deficiencies and then a week later this started so instead of using the recommended 1 tsp I been using about 1/2 tsp per gallon. But thank you for the help I wasn’t sure what it was and was kinda thinking leaf septoria

[ChadWestport]

Looks like a root zone issue. Like gbauto mentioned, the spotting looks similar to calcium deficiency, this can sometimes be locked out by Ph issues. Does this plant drink the same amount of water as the others or is it usually still a little wet when the others are ready for more?

[Desil14]

I’m pretty sure I have some root rot due to high temps in the beginning of the grow and not putting a fan in the tent until week 3/4 so I’ve been doubling or tripling up on the hydro guard. But they both seem to just keep growing White roots although they have grown into one big ball together.

[ChadWestport]

I haven't run hydro myself, so I'm not the best in that area. It's odd to me how multiple plants of the same strain can be eating from the same food source and yet one of them has problems. My only guess could be inconsistencies in the amount of bubbles it receives from the air stones compared to the others (if air stones are used under each root zone) or if it is the closest to your pump and it gets a little extra heat. I'm really kind of stumped on how that is. If that was the only plant to get root rot early on, that might just be the answer, never fully recovered.

[Desil14]

Sorry I didn’t put it already but ones a dark devil auto from sweet seeds and the other that’s not having problems is gorilla glue auto from fast buds. I have two air stones one on each side of the reservoir under each plant.