New growth issues. Fungus or magnesium deficiency?

Hello all, first time grower here.

Growing in Conibo Coco with build-a-soil coco mineral mix. Feeding botanicare kind base, grow, vitamino & pure blend tea, cal-mag, silica, hydroguard & Tribus. Following chart from Botanicare for coco at half strength? Growing under LED & I have humidifier dehumidifier on a controller.

ppm 400

pH 6

RH is between 65-70 lights on, 60-65 lights out.

Temp 78-80 lights on, 72-74 lights out.

Lights at 24″ & 55% on 20/4 schedule.

This started out as just a few spots on lower leaves on two plants. It is now effecting most of my plants & some just have spots although some have gotten progressively worse. I'm leaning towards a fungus issue but with no experience i feel like I'm just guessing. If you have any input or ideas I would greatly appreciate it.

How often are you feeding?
I’m no expert but that coco medium seems really dry

Username85 said:

How often are you feeding?
I’m no expert but that coco medium seems really dry

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Right now I'm feeding once a day around 7pm. The top layer of coco seems to dry out quick due to lights I assume. But less than an inch down it's usually still pretty wet. & If I pick up the cups or pots a little water usually drips out even right before lights out.

keithandthegreen said:

Right now I'm feeding once a day around 7pm. The top layer of coco seems to dry out quick due to lights I assume. But less than an inch down it's usually still pretty wet. & If I pick up the cups or pots a little water usually drips out even right before lights out.

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Ahhh okay, that’s all I had here lol, don’t want to speak on anything else since it would only be a guess. Hopefully one of the more senior growers here can help you. Good luck