We grow in 100% coco, as well. Keep in mind that coco tends to rob Cal and Mag from plants until enough nutes have been applied to "fill up" the coco. This is why Cal and Mag problems are so common with coco. The way around this is to do your initial wet out of the coco with 300 ppm Cal Mag. Then lightly leach the coco. The extra Cal Mag will rinse out, but the rest will pre load the coco to prevent it from robbing your plants. I learned this technique from the President of the largest coco importer on the West Coast. His warehouse just happens to be very close to us and we buy direct from him. He's the one who supplies all of the distributers most people purchase their coco from. His knowledge of the medium is quite extensive.
https://www.rollitup.org/indoor-growing/407048-20-000-watt-medical-grow.html
