ZenBlue Spare UV Bulb Direct Replacement for ZenBlue CW-55 Clarifier, 55-watt

Finally put the light in and it lasted two weeks. My first UV bulk lasted a little over a year when the light changed from blue to purple.When i went to backwash the filter I noticed there wasn't any light from the Clarifier - I backwash every Sunday and had put the bulb in two Sundays ago. Very disappointing considering the amount you charge. NP

Replaced my old bulb with this (same) one, neither worked