Keeping humidity in (humidity isn't going up after misting)

[Louis Charles Bruckner]

Let's say, hypothetically, that the sensors are indeed correct. What would I have to do to keep the humidity in?
(the top is acrylic plastic, tightly seals the top of the tank)

Looking at the picture I don't see any vents except the built in ones in the front of the exo-terra.

What is the 3D background made of. if it is a hydroscopic material it could be soaking up all the moisture.
and hasn't gotten saturated yet.
also with he rise in ambient temp it is harder to keep humidity up also.
I also see that you are using a aquarium thermometer. That will take a bit to register quick changes
in air temp. I would get one that is made for terrarium use.

[Necromencer]

No vents in the top (yet, I need to fix humidity first)

The 3d background is made of aquarium-safe expanding foam, you may be correct in saying that it is soaking all the moisture up.

The picture I sent you is quite old, I don't use that thermometer any more (hence the two digital ones).

[Necromencer]

Update: Pic taken today. Tank finished. You can see the cheap hygrometer at the bottom reading 40ish%.

[DartfrogDan]

I've been having trouble keeping my humidity up as well so i think that may be down to the glorious weather we've been having

[Necromencer]

Glad to know I'm not the only one.

It's been abnormally hot here in Liverpool.

I think the low humidity is one of two things:

1) Incorrect hygrometer readings
2) not enough water going into the water (spraying)