Re: Best digital humidity controller
From the your request, it sounds like you are hoping for a humidity sensor that you can leave in your viv (with a further desire for wifi connectivity). You aren't going to be able to find a reliable sensor that be left in-place.
In a thermometer, the material doing the detection (alcohol, mercury, a metallic strip) can be sealed away from the object that needs to be measured (like the water or air whose temperature you are trying to measure).
A hygrometer, in contrast, has to be in contact with the material it is trying to measure because, unlike heat, one cannot measure moisture content of air without "touching" that moisture directly.
This is a problem because temperature changes in a high humidity environment can lead to condensation. A hygrometer with water condensed on its detector is useless/unreliable and may remain so even after the condensation has dissipated. In a frog viv, misting and high humidity lead to wet and unreliable hygrometers.
Most people use their hygrometer to aid in tuning their misting schedule and ventilation parameters to maintain the humidity conditions they want rather than relying on a constant humidity reading as a control strategy. I suggest you do the same.