Mine did that too. First it was in the 60's, then overnight it was in the 20's. I did better putting a quarter cup in the narrowest chamber almost every day. I think next time I will put a small dish in there, might be easier to control
If it is really humid where you live, you may not need to add water. Are you sure the hygrometer is reading accurately? I've had one that stayed at 60 all of the time, even when I added water and found it was stuck there and needed to be replaced. Do you have a backup?
Yeah, I calibrated both of mine the other day, and they are both about 2 degrees low. It was reading around 40% before I put the fan in. I took ot the sponges that I had in the water, and it came down a bit. So I took the extra water bowls out, and it came down a bit more. When I last checked it, it was at 55%, which to me is still too high, so I put a piece of paper towel in it. We'll see if that helps.