About Biocanna in cocos

is it just to use biocanna to cocos as medium? or is it for soil only?

I used it in Coco and it went terrible. I wrote Canna and they said that the Bio line was not for Coco. Something about the CEC exchange not working. I can dig up the info. They told me to use an Organic Peat based medium. I use a Happy Frog and Pro-Mix blend.