My first grow was outdoor coco. 
Learning curve for sure. Proper Feeding, EC, and PH are key.
I was using GH then.
Have use MC 1 part.
Now using Jacks with success.
Glad to help where I can. 
I’m still working my way thru this read…
https://manicbotanix.com/coco-substrate-and-hydroponics/
https://manicbotanix.com/rtwdtw-hydroponic-growing-systems-v-recycling-systems/