The answer is yes if your humidor is equipped with a sponge or foam humidifier (often called Credo humidifier). If you do not own a hygrometer, our adjustable digital hygrometer is perfect to monitor both temperature and humidity.
The Activation or Propylene Glycol Solution is a solution that contains a mixture of propylene glycol and distilled water. Propylene glycol is a two-way humidification device that works in two ways: it will both humidify and absorb excess humidity in your humidor. It also acts as a bacterial and mold inhibitor.
The frequency with which you need to charge your humidor with the solution varies depending on your climate. We recommend that you do not use distilled water, as it will either 1) humidify too quickly or 2) over-humidify because there is no PG solution to restrict the flow of moisture.
TIP: Some humidifiers, like the Cigar Oasis, the Western Humidor Humifier, or the Cigar Mechanic, require you fill them only with distilled water.