The bat guano would have to be composted, most manures you use are hot - excluding rabbits and worm castings. But if you mix it straight in the medium like you would the perlite at the beginning, it’ll start fucking with the ph once it does start to break down or could burn / fry the plant.

I was thinking he was trying to grow DTW in coco coir an had mixed in organic fertilizer in as to have to keep from using fertilizer with every watering.