Yellowing, dying leaves

Hi, so let's begin with a little bit about the plant:
RQS Jack Herer Auto
Grown in soil with perlite
it's in +/- week 9

I had a problem with magnesium a few weeks ago which i fixed by applying a foliar spray a few times and added a bit of magnesium into the water. I usually water her with PHd water mixed with around 80ml of Biohumus per liter. The leaves started appearing funky a few days ago but I didn't pay much attention to it back then. Mostly the ones at the top were affected and maybe two or three leaves in the middle of the plant were yellow. I was out of town for 2,5 days and couldn't water her. I came back today to this horryfing sight. She is obviously underwatered, but now most of the leaves have this yellowing. In reality they are a lot more yellow than in the photos. My phone made them look a lot more green than they are.

Any ideas how I can help her and save the grow?

anyone?

If all you are giving is this Biohumus you’re lucky you’ve gotten this far.

hotrodharley said:

If all you are giving is this Biohumus you’re lucky you’ve gotten this far.

Click to expand...

What should I give her then?

Sounds like you’re trying to go organic so I suggest checking out Advanced Nutrients Iguana Juice. One bottle for Grow. One bottle for Bloom. I’ve used it and it works. Others here will have suggestions and most will be good. Remember KISS.