Info:
- Fox Farms Ocean forest
- PH 6.2-6.3
- Leaves clawing or curling down significantly
- Chlorosis on older growth
I am seeing a few issues here so it is going to be a little hard without more info.
When examining your picture I am seeing old growth is affected (Chlorosis) and new growth is ok thus far.
The leaf clawing or curling like this is a classic sign of over watering.
I am going to recommend as
@Tracker has that you check the underside of your leaves for any pests just to make sure.
If I were betting I would say it looks like over watering and an possible and/or inconstant watering schedule.
I would...
Trim off all of those damaged looking leaves.
as tracker has stated ...
They aren't helping the plant, and just consuming resources
This will also help if you happen to have any pests on those leaves...

your friend doesn't have any pests.
The new growth looks ok but there are a few specs of concern on the leaves.
I am hoping that this is simply over watering.
I would recommend
Letting your soil dry out.
When it is dry you will need to be careful with watering.
Lift the pot when it is dry a few times to get a good feel for its weight when dry.
I would
bottom water (
water only) and let the plant wick up water as to not over water.
Simply put the fabric pot in a catch pan and pour the water in the catch pan not the pot. The soil will wick up what it needs. You will need to let the pot sit for 20 or so minutes. After 20 or so minutes take the pot out of the catch pan. Be sure to lift the pot a few times so that you can get a good feel for the weight of the pot when it is full of water.
By lifting the pot when it was dry and when it is saturated you will be able to tell when the pot is dry and needs water and when the pot has plenty of water..

I have found lifting and feeling the weight of the pot is the least intrusive way to determine watering needs. Remember cannabis needs to dry out a bit.
I would have your buddy check out
this link....
It has some great info and resources.
This link is also a great resource and will have plenty of info if you to check out.
Please let us know how everything works out!
