COCO COIR Grow medium

[Warlock]

Hi all, im planning to start some Gorilla glu autos. I made the attached grow medium with Coco coir and compost 50/50. Going through the articles i learnt that the ideal PH for cannabis is around. 6.5 . But currently the PH in my pot is 7. I tried using vinegar to reduce the ph but its still the same. Very great if you guys can advice me on this to reduce the PH.
Cheers 😄

[90Gizmo]

Your meter only measures pH when the medium is moist/wet.