Here are some tips to prolong the life of your Sponge Humidifier:

A sponge humidifier can last anywhere from a couple of days to a couple of weeks before it needs to be refilled. It is always best to use a hygrometer along with a humidifier so that you know the exact humidity level inside your guitar case. A guitar should be stored between 40% - 60% RH. If the humidity level of your guitar case is above 60%, discontinue use and contact us. D’Addario offers a standard hygrometer and a smart hygrometer call Humiditrak.

1. Never store your instrument near a heating element such as a radiator, forced air heating vent, etc., and try to keep out of direct sunlight (through windows) for an extended period of time. 
2. Use distilled water! Tap water has minerals, etc. that can compromise the effectiveness of the foam and oxidize the hardware of your instrument. Filtered water can be used as well.
3. We highly recommend getting a hygrometer to monitor humidity level inside your instrument case.