Cheers guys,

Ive just acquired a ph meter and up and down so ill adjust my nutrient solution.

Rusty: Thanks for addressing the 'bite' issue.
With regards to overwatering, would you recommend that i let them dry a little before resuming ph adjusted nutrient solution. I didnt think overwatering was possibly with coco, but thanks for the info, i dont want to continue damaging them. The water flush was because i thought they were suffering nute burn

I'll give them a feed a post an update, hopefully signs of recovery

Thanks again