We have the same setting, a three sided barn with a fan and misters. We have a local Amish mill that will load up the back of our truck for $15, and it fills the barn and lasts about a month (with about 4 head on it). The last two times the mill has been down, so we went to the local city parks and got mulch for free. It is not as consistant as the mill mulch, but still seems to work well. W have never lost hair on knees, but I could see it happening if your mulch was too large...