2 plants, one reservoir, one has problems

Okay so one of my plants, about hallway through flowering, is starting to show damage on the leaves. I'm still working out the diagnosis, but my question is, why is this only happening to one plant? Both of my girls are in a single DWC tote, so they are getting the same nutrients, same PH water. They are the same strain. Is it just a more sensitive phenotype? Could it be light related (each plant is under a different 300w blurple light)? Also, the plant with the damage is bulking up faster.

I'm new to hydro so I was just surprised. I would have assumed a deficiency would affect both plants. Now I don't know what to do, because I don't want to damage the healthy plant trying to fix this one. In the future I think I'm going to use separate buckets to avoid this, but in the meantime, any suggestions would be appreciated!

Each plant operates a bit differently so deficiency may be present in one and not the other. Maybe you should consider a broad spectrum trace supplement and calcium & magnesium supplement. Shouldn't bother the other plant to add those if needed. Good luck

Try to find a cal mag with low nitrogen

See NPK Raw dry nutrients. They have separate Ca, Mg, N, ...

Thanks guys! I actually just picked up some CalMag and haven't seen any new damage since adding it.

Thought I had lockout issue because of PH for about a week, turned out my PH meter was junk. New meter, CalMag, and crossed fingers! Almost to the finish line.

My understanding is that drugstore Epsom Salts provides the CaMg without adding N