Dry desert vivariums are reasonably simple to set up typically. A high temperature from a suitable reptile heater like a ceramic bulb, together with some dry substrate such as reptile-safe sand and you’re well on your way.
However creating a humid “rainforest” vivarium requires rather more time and effort if your exotic pets are to thrive in this kind of environment. Even more so, regular maintenance will be required if the environment is to stay constant.
Humid vivariums are ideal for a whole range of reptiles and amphibians including tree frogs, poison dart frogs, iguanas and water dragons; all of whom hail from the moister parts of the world.
When creating a moist, humid environment one obvious idea is to limit ventilation in the cage. This will keep moisture in thus helping you to create a humid rainforest vivarium far easier than in a cage with plenty of air movement. However stale, stagnant air can cause mould and fungi to grow so in contrast to what you may think providing adequate ventilation is essential to creating a moist environment.
There are three common ways to add moisture to a vivarium and thus keep the humidity up. The first of these is to spray the terrarium with a house-plant spray gun containing tepid water and this can work well. If you go down this route ensure that you buy a new spray gun specially so you can be certain it has had no harmful chemicals in it and remember you will probably need to spray the cage several times a day to keep up moisture levels.
The second method is to include a body of water in the cage. By having open water in a warm environment a degree of evaporation will occur which will help to keep the tank humid. Care must be taken with this method though as some animals like poison dart frogs may risk drowning if a large body of open water is present in their cage. In contrast lizards like iguanas may appreciate this open water and may even drink from it or bathe in it.
A slight modification for the smaller or more sensitive herptiles is to place an aquarium heater into a small container of water which can be placed behind some gauze to prevent your pets coming into contact with it. However the heater will warm up the water, leading to evaporation. You will still need to check the water level daily to prevent the container from becoming empty which can cause damage to the heater.
The third method is to use a special mister designed to keep reptile cages moist and these can be bought from many specialist reptile stores online. Artificial waterfalls are also available and will help to increase the humidity in the cage though as with the previous method you will have to be careful to ensure that the equipment does not run out of water.
There are a range of houseplants from bromileads to figs which will thrive in a warm, humid environment which accurately mimics their natural habitat. The use of live plants, while requiring more effort from you to maintain them, can also help to raise humidity but also absorb excess water and hence avoid the risk of water-logging. Try to keep plants in their pots where possible – burying them just below the substrate – so that they can be easily removed or fed if necessary without having to dig them out of the substrate.
One final point I’d like to make is the importance of monitoring a vivarium setup like this. If your cage dries out because of lack of water or lack of warmth you could find yourself in rather a mess. So it is wise to not only check your equipment daily to avoid any nasty surprises but also fit a digital hygrometer which will measure the ambient humidity in your cage and check this morning and evening to ensure your vivarium is within reasonable boundaries.