Here are some tips:
one should rely more on larger model in doubt, then it does not take long after the airing again until the desired humidity is reached. One can indeed exhibit the device also.
The airing lowers especially in cold temperatures below zero, the humidity indoors rapidly. So if you want to sleep with the windows open, for that is nothing.
The Hygienmittel costs money, but it's worth it to me, because I do not want bacteria spin in my living room.