The Hygrometer is working perfectly. As soon as i take it out the humidity drops. It's a ETAN REPTI ZOO MODEL:SH124. There things are accurate to 0.3°C and 0.1% humidity. So i don't understand this at all

It could still be broken and "working" fine in a since. but the fact that it says 99% constant and your substrate is bone dry, and you live in PTA dry and hot weather. Just check your hygromator, buy yourself a new one and do the test.

Here is one of my Hygromators, in one of my containers.



The temp is 16degrees inside the spider room.

My substrate is moist, as you can see in the picture.
and my Hygromator is sitting just over 80% humidity.

I reckon best would be to take the hygrometer to a shop that sells them, or the zoo and compare against others to see whether it reads within the same average range.

Marius wrote: I reckon best would be to take the hygrometer to a shop that sells them, or the zoo and compare against others to see whether it reads within the same average range.

The best place would be your friendly, city or national weather office. In the USA we'd look under NOAA in the phone book, but I don't know the system in SA. They'll either tell you how to check its accuracy, how to calibrate it, or they'll do it for you. Or they'll roll on the floor, laughing their fundaments off at your humidity gauge! But, at least you'll know where you stand with that gauge.

This should give you more or less an Idea.

Weather in South Africa – Pretoria

cascade wrote: This should give you more or less an Idea.

Weather in South Africa – Pretoria

Am I mistaken or are these people in Norway? If so, that's not going to help.

You need the national weather service for South Africa, maybe these people .

Remember, you don't want to know what the humidity is at one of their weather stations. Humidity in nature is so chaotic that it could be radically different 10 m from their gauge. And change by 10% every hour.

You want their help calibrating your humidity gauge, a completely different question.