I agree with Karen: some coir is like fine powder - in my opinion, only useful for amending soil outdoors. In pots, it holds too much water, no air, and clogs up any mix you add it to.
Some coir is nice, big, coarse fibers. I liked that for "opening up" a seedling mix that was too powdery and not aerated enoguh (I tend to overwater trays). Now I usually use screened pine bark for that, but the coir seemed to help the one time I used it for seed starting.
I've read that some coir is sold as chips or pieces but never found any.
HOWEVER, I've also read that some coir is salty when sold. If true, that would kill a young seedling pretty fast! Now, I hydrate my coir in a wheelbarrow over several days up to a week. I fill the wheelbarrow with water and let it soak for at least an hour. Dump excess water. Try to squeeze out more water. Refill wheelbarrow. Repeat.
If any companies keep selling salty coir, it will get a bad name and people will stop using it.
