Humidifier filter additive

[Steve83]

I was curious what others use to cleaning their humidifier filters with. The water in the reservior "evolves" quickly, and I'm just going to play it safe and empty/clean it daily.

I grabbed two extra filters with intent to replace them every 2-3 days, but wasn't sure what a good/economical soaking agent would be for them., so they can be rinsed and dried for reuse. I don't mind spraying a bit of bleach in the reservior and rinsing well, but that procedure would eat the filter material pretty fast.