Magnesium Def or too much?

hey guys, one of my plants is showing rust spots on some of her leaves. She is the only plant out of 80 that is showing these signs. It has gotten a little bit worse in the past few days but its a barely noticeable difference.

Im confused though, the Sticky in this section says this happens when there is Lack of MG but i supplemented MG. could this also be because of too much? I diluted my reservoir with more fresh water in hopes of it stopping this.

here are some pictures..

anyone? dfghtdtjyujrndfhmjn (post was too short)

1 plant out of 80 in hydro? That's kinda bizarre

i have a mother in soil with this problem... would also like to know.

are you misting?

Calcium def can cause the leaves to deform like that and it can also be caused by deficiency due to PH.

sometimes misting, especially in hyrdo, hurts the plants. 1 in 80 sure is weird