Hi guys, just got my first setup from spiderfarmer, i’ve got Tropicana Cookies Auto on hydroponics. Unfortunately i have been having the issue you can see in the pic. The bottom leaves seem to be rusting which should be a ph problem, but the ph has been more or less stable (5.7 to 6.3 range). Looking for help, I flushed the solution a few days ago and replaced it with a new one but the problem persists.
Thanks in advance
https://imgur.com/a/x75FSsW.
Rusty spots on lower leaves in hydro can be from a few different issues. pH swings can lock out calcium and magnesium, which show up as rusting or spotting. Try to keep your reservoir steady around 5.8‑6.0 and avoid big swings; it’s worth calibrating your pH pen if you haven’t recently. Autos don’t need heavy feeding early on, so double check your EC/PPM and consider using a Cal‑Mag supplement if you’re using RO or filtered water. In hydro, high water temps and low dissolved oxygen can also stress roots and cause leaf issues – aim for water temps in the mid 60s°F with plenty of aeration. Keeping those parameters in range usually clears up rust spots within a week or two.
Hey! I know, I am a bit late here.
The rusting on your lower leaves could be a nutrient lockout or deficiency (iron, magnesium, or calcium) even if your pH looks stable. It can also be normal aging of lower leaves or stress from water temperature/oxygenation. Keep an eye on new growth if it looks healthy, it may not be a big issue; if it spreads, check nutrient balance and water conditions.