COCO COIR !!Help!!

[Challir17]

Here are x10 Northen Lights Autoflowering
3 Months 15 days old
Growing in 16L Fibre Pots
Coco coir medium
2L of water every 3 days
600w Light (1 Lamp for 10 plants I know )

The Dilemma -
they were all growing absolutely fine until flowering stage. I first noticed brown spots on plant I read it was PH imbalance in soil or root problems. The leaves were also turning yellow and had neutriant burn so I just watered them with PH balanced water for 2 weeks and still no difference only getting worse.

I hope I don't damaged my babies I blood sweat and tears have gone into these. I need help asap

thanks in advance

[Canuck147]

105 days old autoflowers - hmmmm - your sure they aren't ready to harvest?
Looks like your bud size suffered a bit due to your lighting.
I have 2 plants right now at 95 days - one has trichomes just turning amber, so her turn for the scissors is tomorrow or the next day.