A. Only as often as necessary. Once your hygrometer dips below 65%, you should add more distilled water. (The "normal" range is 65% - 70% RH.) Of course, how often you need to refill also depends on both, your cigar humidor itself, and the type of humidifier you have in it.

If you find you're refilling too often, you may need a larger or a better model, like the XiKAR crystal-based humidifiers (shown). They regulate much better and last longer, too.

Remember to use distilled water or polyglycol solution only to help avoid mold from forming on the humidifier. Note that some humidifier manufacturers also make their own solution to go with them.