Coco is the easiest medium to grow in unless your going to grow 100% hydro. It is totally different to soil and should be treated as such.
Every time you water your plants in coco you give the roots 30% oxygen which is coco main strength. Plants love growing in it. You will always need calmag when growing in coco. I'm growing 4 auto in coco at the moment. I feed everyday with nutes and calmag and I use a root enhancer, shogun to be exact. Make sure that the nutes you are using are designed specifically for coco. I use canna coco plus and feed them canna coco a and b. Of course you have lots of other things to get right like temps of grow room air flow etc, but I swear buy canna products each to their own I know, but give it a crack. All the best with your grow