Different humidity day vs night
 

I have a small tank for keeping a few small Angraecoid orchids, including a Dendrophylax lindenii, made of these items:

• an exoterra tank, the Mini Tall, 12 x 12 x 18
• an extension cord by ReptiZoo EZ Thermostat Timer Controller
• a humidifier/ fogger (ReptiZoo 4L), a couple Barrina T5 lights, and an AC Infinity fan.

I'm trying to achieve a specific humidity regime of 50% humidity during the day and a 95% humidity at night.

With the ReptiZoo EZ Thermostat Timer Controller I can set a humidity range and plug in the fogger to follow that, but it doesn't allow me to change the humidity setting for day vs night as far as I'm aware.

Does anyone have a solution for this? Happy to buy a new item if need be.

Would be a huge help.

just a guess. But once your lights go out. Shouldn't the humidity in the tank rise naturally.

If the temperature drops, the humidity goes up - cool air holds less water than warm air, that's the "relative" part of "relative humidity". So when the lights go off, I think you'd have to go to some trouble to NOT have the humidity rise... not only natural, but inevitable without intervention.

That makes sense. In that case, how do you recommend I achieve that humidity regime then? Turn the fan on during the day? Is it worth using the humidifier at all? I think the terrarium would dry out too much if there was no humidifier.

You will most likely need the fan during the day. Where is the humidity level with fan and lights?

50 -75% humidity should be fine for the Angraecoid's. I have grown other Dendrophylax species around the same. Never gave Dendrophylax lindenii a try

See what it does. Don't depend on just programming and ignoring... observe. The plants will benefit from a day-night differential in both temperature and humidity. Programming can be useful once you know how the system reacts to conditions. But you have to know first before you can program it to automate.

There are several factors to consider when RH is calculated (temp, absolute humidity, pressure, etc).

To make things the more practical and easy, the key is to have the highest temp differencial between day and night temps.
You can use those portable higrometers to confirm RH values inside the tank.