Coco does not have an NPK value, nor does it contain any additional organic matter to feed the plant.. You cannot "feed" coco.. Coco does not "feed" the plant.. It is not soil.. If you are using bio tabs, then the Bio Tabs (compressed dry nutrients) is what is feeding the plant.. Not the the coco. Coco is popular because of its ability to retain nutrients.. It does not provide the plant any NPK. Of course bio tabs will "work" in coco.. Is that what it's intended for? Highly doubt it.. Keep in mind that most of us only grow weed.. Companies like Bio Tabs make their money from, and market to, veggie and cash crop growers/farmers.. And they grow in soil.. You can use a flat head screwdriver to paint a portrait.. It will work.. But a paint brush would work better.. I think that's the point Slow was trying to make.. That yes, bio tabs will work in coco.. But they will obviously work better if used as intended (which is in soil). But again, like Slow said, as long as you are happy with your results, whether they are mediocre or excellent, that's all that matters..