I am using aspen in one tank and coco husk in the other,coco husk is doing nothing different for humidity either...I just got a bag of Eco earth and I will be trying that next. Think it will hold humidity way better than coco husk,it's obvious already as it's damp in the bag....

as as for the coco husk and aspen,well both tanks are set the same and both tanks holding humidity the same..I like aspen to be honest