Humidity In Rack and Tub enclosures?

So I am having trouble keeping my humidity up in my racks. I am misting daily but within a few hours the humidity is bottoming out I'm thinking about just setting up some humid hides instead of trying to mess with the ambient humidity in the entire tub. what do you guys think any suggestions will be appreciated.

I am housing my adults in 28qt sterilite tubs with a warm end of 87 and a cool end of 80. ambient room temp is 80 and ambient room humidity varies from 25%-40%. humidity in the tubs varies from 25% on the low end to 70% depending on how recently i misted the enclosures

Also I am using aspen bedding as it is absorbent and easy to clean out. However the fact that is absorbent is a double edged sword i'm sure. I am tempted to switch substrates to try and trap humidity in the tubs

What are you using to measure humidity?

A Zoo med Hygrometer I got from the Tye Dyed Iguana

In the winter i had very little trouble with humidity because I had a small forced air heater blowing over a Container of water which help bring the ambient room humidity up overall

Dial type correct?

If so that might be your problem, they are known to be inaccurate and can easily be 20% off.

Do you have anything to comparison it too?

No it's Digital a one i have the same type in my Bator that seems to get the same readings

I just double checked and it is an Exo Terra

Are the tubs open or covered?

They are in a rack

What I mean is if the lids on the tubs on or off. I had a similar problem and keeping the lids on controlled my humidity level.

You have to make sure that you have hole in both the front and rear of the tub so that air can exchange