Sample leaf problem - coco and salts

Only one plant is doing this but it had a fan blowing directly down on it.

2g pots of pure coco, Jack's 3-2-1, watered with Blumats. For my 27g reservoir I mix 75g-50g-25g. It kinda looks like cal or mag.

Are the leaves that weren't infront of the fan displaying these symptoms, or only it? Too much wind can cause a leave to dry out and get spots like that. If it's only on leaves directly infront of the fan, don't worry about it. Just try to adjust your fan so that it isn't stressing your plant anymore.