Not so Mellow Yellow

Hi guys, so this is my 2nd grow - bit of a newbie. I’m growing 2 x AK47 Autos that are about 4 weeks in. A couple of weeks ago I started getting some issues with burnt leaf tips.

Bought a meter and realised that the PH was way too high 7.9. Subsequently corrected it and new growth appears ok but the leaves that originally had minor brown edges are now dying very quickly. Not sure if I have a new problem or is this normal for mildy damaged leaves to progress to dying completely?

Growing in Coco Coir and using CANNA A+B with Cal Mag supplement and occasional molasses. Any advice would be helpful - would obvs prefer to catch any new issue early. Thanks for the help

I would think the problem could possibly be molasses in the coco causing pH problems.

Also, in my coco I triple wash it first, then soak, charge with nutrient and calmag, and PH it for a day.

Did you properly soak and precharge the coco before using it? What kind of coco was this?

How are you measuring your pH?

are you also measuring ppm/ec?

Thanks for this! Wasn’t aware that you need to rinse Coco first! Doh!

I bought a PH meter. It indicates that the PH is 5.8. No I’m not measuring ppm. Not even sure what that is! Will need to give it a google. Last year I think I was lucky. Grew a large Amnesia Haze (140g’s) in same medium and didn’t check PH once. Beginners luck! I may hold off the molasses for a bit based on your observation.

Which brand coco did you use?? Canna would be the most forgiving for this mistake, and fixing it is still a pain. Check this video out describing what goes on during rinsing/charging your coco
I don't think they say you need to rinse it, but I still do for most brands; I always triple wash mine. Buffering however is still important no matter what.

Ok that’s great advice - I’ll make sure I charge the medium moving forward. Apologies meant to add the brand of coir to last reply. It’s this type (attached).

Why are you using molasses in coco with synthetic nutrients?

A friend recommended it. But based on Nizza’s response I’ll be holding off. Looks like it’s suited for soil not coco - you live you learn!