Sooner or later all the misting nozzles will clog or start to function improperly, but with a little maintenance you can take care of this problem. Most clogs are caused by one of three different things, rust, minerals or algae buildup in the nozzles. Install a 200 mesh filter in-line, or if problem continue use cartridge water filter that can be purchased at the local home center. At any time you can open the nozzle and soaked in vinegar, bleach or soap overnight to remove deposits or dirt.
