I am not a fan of coco husk but it looks to me to be salts leeching out from the husk or your water. if its happened before and you re-potted with fresh husk and it did the same thing, you either arent flushing the plant enough w/good water or you have really hard water. More fresh water like Rain water.
I dont know what you use for fertilizer and that could be the source of the fallout. looks more like a salt formation to me.
The word salt is a general term which applies to the products of all such acid-base reactions. The combination of hydrochloric acid and sodium hydroxide produces common table salt.
The H(+) cation of the acid combines with the OH(-) anion of the base to form water. The compound formed by the cation of the base and the anion of the acid is called a salt.