Here's what I see. Bottom photo, upper right plant. Is this the subject plant? Look at the Vermiculite in each pot, all of the pots, except the upper right has Iron Bacteria on the Vermiculite. That is indicative of Iron bacteria in your water source. As a Water Drilling Contractor, and Grower for the last 30+ years. Iron will cause a few things, one is Nute lock. The roots will also get fouled. Again don't know if that's your subject, but I would start by having you water analyzed. Call a local Water Conditioner sales guy. Tell him your interested in equipment for your water, and want a FREE water analysis. I have offer these for decades. It's a selling tool, but the info in it is excellent, and it's free! Make sure they send there water to a lab to be analized. If not the results are bullshit! Look for a dealer that sells iron filters. This should give you a 10-15 parameter report on what's in it! Every thing from how many PPM of Iron, how many Grains per Gallon (Hardness/Calcium Carbonate), to Ph, (7.0 neutral), PPM OF Sodium Cloride(Salt), ETC.....