Hmm this is a difficult one - he didnt flush the perlite or coco - which i have heard is key in pH stablising
However - theres something in that coco which is telling your water input that it doesnt want to budge - so that means there is something in there - whether it is the perlite or coco i have no idea.
Generally when a pH goes in and comes out one way or another - it has passed through a pH and reacted and the final result is a blend of the two.
Your water has reacted with something in the medium which has shown you that the medium is high
I know perlite usually has a pH of 7 - maybe we need some coco experts in here to help you out - but maybe its the flush of the medium before planting which is setting you back - thats the only thing i could find from a little coco research
However - theres something in that coco which is telling your water input that it doesnt want to budge - so that means there is something in there - whether it is the perlite or coco i have no idea.
Generally when a pH goes in and comes out one way or another - it has passed through a pH and reacted and the final result is a blend of the two.
Your water has reacted with something in the medium which has shown you that the medium is high
I know perlite usually has a pH of 7 - maybe we need some coco experts in here to help you out - but maybe its the flush of the medium before planting which is setting you back - thats the only thing i could find from a little coco research