Are you calibrating the meter? What do you mean the pH of the feed is about 5.9? Using a meter you should know exactly what the reading is. Finally do you use a household water softener that uses sodium? I'd expect a Ca or Mg lockout but if you are using sodium softened water I'd try using a source prior to the softener.
Yes, I'm calibrating the meter. It uses a three point calibration and various steps of PH. I'm using unadjusted Scottish water, with no softening. I say 'about' 5.9 because the meter is sensitive and the number moves a bit while measuring, but its +/- 0.1 from 5.9. Last plant I grew, I didnt do any PH adjustment and it grew without an issue. The change to coco is the big change here but dont really know what the deficiency is.
Last grow was in soil and standard plastic pots. This grow is in 70 coco / 30 perlite in Airpots. The soil grow, I basically did nothing - no temperature or moisture control, no PH balancing and the standard feed schedule (albeit feeding when the top soil was dry instead of daily). The only issue I had with the last grow was fungus gnats. This grow, I've had no pest issues yet. But the change to coco with airpots opened up some new challenges as I'm finding out with this issue.
I was going to suggest moving this plant to what last worked for you, soil. Unfortunately it's an auto and my understanding, although I've never grown them is they don't like to be transplanted.
Cheers bud - if I find and fix the cause, i'll certainly report back. Will re-calibrate the pen tonight and see if the mix I've been using is accurate or not.
Maybe 2 or 3 cheap pens instead of 1 blue lab?
Hi, I'm kinda new to this as well and only grow in clay pebbles, but as you are a fellow hydro grower I thought I'd share my thoughts..... I think you are watering too often. I let my ph swing from 5.5 to 7.5 and never had this issue, but the one time I grew in media that holds water I had the same problem you're having (plant died in the end) turned out I over watered her. I can go a 2 days without watering these before they start to ask for water.
Well, I got super paranoid since the posts earlier so I went to re-calibrate the pen and retest what I'd made. I discovered that it was indeed low and the calibration hadn't worked properly. After calibration, my mix was reading around 5.4 so it's not within a comfortable range. I've remade the batch to be bang on 6 now and will monitor it over the next few days. Thanks for your help (and everyone else!), I'll post back if things start moving in the right direction.
Sadly the problem started when the first leaves appeared regardless of watering frequency and continued up until today, so it's likely PH or nutrients i'd expect. We will see for sure in the coming days. Going to bump the humidity up a little too, hopefully tomorrow.
Dude is straight up.
Perfect. I grow in coco/perlite and you want to be 5.8. They looked like they were having pH issues. I float my res up to 6.2. Watch the next day after adjustment you usually bounce up. But after that it holds fairly stable and don't rush the pen. You can pull it too early while it's still going down and hasn't reached the actual reading. It frustrates me how long it can take.