The Laguna PT1522 is the correct replacement UVC lamp for the following:
The Laguna PT1522 Pressure-Flo UVC Lamp for PT1506 is a replacement bulb for the Pressure Flo 3200 UVC Filter. The 25-watt Pressure-Flo lamp fights the growth of single-celled algae organisms in your pond water. This UV bulb should be replaced once a year to achieve the best results.
Laguna PT1522 Pressure-Flo UVC Lamp for PT1506 specifications: