When hollow pith is cultivar-normal vs heat, water, or excess-N stress in hydro crops.
Why plants pale after a reset—and the order to check pH, chelates, temperature, and shock.
Separate heat/light/VPD cupping from overfeed claws and edema patterns.
Symptoms and fixes when pumps suck air, lose prime, or rattle—before blaming nutrients.
Causes and prevention for catfacing beyond cracking and blossom-end rot.
Environment and harvest timing when hydro lettuce turns bitter or bolts early.
Tell hard-water spray spots and salt film from true powdery mildew before you spray.
Triage rapid EC climb from concentration, under-top-off, or meter error before tip burn.
Interpret daily pH drift direction as uptake and water-chemistry clues—not only a dose trigger.
Diagnosis tree when plants share one tank but grow unevenly—light, flow, and plant history before rewriting EC.