Made it 200 days without refilling the Musik Tent reservoir, while still maintaining very controlled humidity in a guitar sound hole.
How can the ambient humidity be so low when it's so humid outside? Humidity depends on temperature, which is why it's referred to as relative humidity. It's essentially the moisture content of the air relative to the temperature. Even if it's 90% RH outside, the humidity inside may be much lower due to air conditioning. Generally, the cooler the room, the lower the humidity. We tend to maintain around 74 to 75 deg F, so you'll see that the ambient (room) humidity hasn't exceeded 45% yet.
Damon DeBusk is a multi-patented product designer, process and quality engineer, project manager, author, and inventor of Musik Tent Instrument Humidors and HumiForm Cigar Humidifiers.