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How to keep humidity in terrarium high, without constant misting?

Jun 10, 2018
I've setup a new terrarium, and I'm having some issues keeping the humidity high, without overflowing the tank.

The tank is a Exo Terra Natural Terrarium Large Wide, which is 90cm x 45cm x 45cm. (I also have a second smaller one, which is the Exo Terra Natural Terrarium Medium Wide, which is 60cm x 45cm x 45cm).

For misting, I'm using a MistKing Starter System, with two nozzles - one at each of the front corners of the terrarium. Target humidity is set to 75% (with 5% difference, so it starts misting when it falls to 70% RH). The reason for this humidity is to get the sphagnum moss growing quickly. (Optimal humidity for this is apparently around 80%, 23-25 degrees C, and 200-300 PAR).

For lighting, I'm using a HLG LED system - around 135W for the Medium, and 240W for the Large tank. I've dimmed it slightly, and it's around 280 PAR in terms of lighting.

For substrate I'm using the Epiweb IIS system (basically black mesh that plants can grow on), so there's a pool of water at the bottom, the Epiweb and then sphagnum moss on top.

I do have a heating coil underneath the Epiweb to heat the water - however, it seems with the LED lights, it keeps it warm enough anyhow (around 25 degrees Celsius), so I have that off at the moment.

The top of the Exo Terra is metal mesh, so I've put a little bit of plastic cling wrap, to try to reduce the evaporation.


The misting is working well, to keep the humidity around 70-80%.

However, the issue is, with all the constant misting, the water level keeps rising, and overflowing through the front. Also, I'm going through my misting reservoir super quick.

What do people suggest, to keep the water levels in check, whilst still maintaining 70-80% humidity?

Would completely covering the top with say, acrylic sheet help? Would a little fan inside the tank help? Or what else?
Aug 4, 2008
Mistking nozzles are overkill for such a small space. For this kind of application an ultrasonic fogger would work much better. They will still introduce extra water into your set up, but at a much lower rate than a couple of misting nozzles.
Oct 21, 2021
I have the ultrasonic sensor in mine. Does well at keeping humidities between certain percentage and it doesn’t overflow with water. Keeps the sphag moss damp and the soil media fairly damp but not super drenched. Seems to be doing well with what I have. I define watched the sundews grow stronger. I’m about to pull the pitcher and VFT out to get them ready to go dormant though.
Apr 19, 2012
Greeley, CO, USA
For just about any carnivorous plant, their own rates of transpiration and the evaporation from the soil will provide more than enough humidity for them; most really don't care about humidity (especially the ones visible here), and will want for light, light, and more light before anything else (save clean water) to do well.