The filter on the probe should be replaced when it is damaged or dirty.
- Turn the filter counter-clockwise to loosen it.
- Remove the filter from the probe. Be careful not to touch the sensors with the filter. Without the filter in place, the sensors are easily damaged – handle the probe carefully.
- Install a new filter on the probe, and tighten it so it is finger-tight. Make sure the filter sits straight and meets the threads properly.
Order new filters from Vaisala.