My PVC cont. feeder was great until summer humidity took over and the feed didn't flow as well from the storage area into the trough. Same with the feeder I made from buckets and flower pot trays, no flow in humid weather....and we don't even get the high humidity that most folks get.
I've found that my trough feeder is not so tempermental. LOVE the idea in the pic above, though! Cool, cool, cool!