When the dial valve is set on filter, water is leaking out the backwash line. Why?
A small amount of debris or sand may be trapped between the diverter gasket and the valve plate. To clean the valve, push down on the valve handle while the pump is running. This will flush out the valve and usually resolve the problem. Note that when you push down on the valve handle, water will pour out of the backwash port. If flushing the valve out does not resolve the problem, then you will need to remove the valve cover and visually inspect the diverter gasket for debris or damage. Clean valve body and diverter gasket with water or replace diverter assembly if necessary. (Please keep in mind it is recommended to always turn the pump off when changing the filter head setting. Failing to do so will result in stretching and distorting the diverter gasket, causing a leak out the backwash line).
