How to Build a Bioactive Terrarium for Your Reptile: An Introduction

Almost anywhere in the world, there are millions of both seen and unseen natural processes happening all around us. From the decomposition of organic matter beneath our feet, to the different cycles present and flowing all around us, our unique planet has many tools for maintaining its life-giving balance. And each living organism on this planet has a specific role to play.

The maintenance of life on Earth depends on the four cycles of nature: Oxygen (Photosynthesis), Hydrogen (Water), Nitrogen, and Carbon. These cycles create the water we drink and the air that we breathe. With that in mind, envision a forest floor; deciduous, tropical, temperate or even sparse desert environments all have different ways of recycling a limited supply of nutrients in order to maintain the efficacy and living conditions of the biome as a whole.

In this article, I will discuss how to build a bioactive terrarium that closely replicates these different processes and cycles in a captive environment. Although commonly kept in unfurnished, sparse, or human-decorated terrariums, it’s important to keep in mind that reptiles (even those which have been captive-bred for generations) are wild animals at heart. Each has wild instincts and behaviors which evolved as adaptations to their natural environment, and these instincts must be nurtured and reinforced in order for a captive animal to experience a natural, healthy, and balanced life.

To this end, mimicking the cycle of nature by creating a self-cleaning, bioactive terrarium is the best standard of care for keeping reptiles as pets.

The History of Bioactive Terrariums

Since the reptile and amphibian trade began gaining popularity in the 1970’s, there have been a few innovations where standards of care are concerned: UVA and UVB from Arcadia Reptile, automatic misting systems from MistKing, nectar diets from Pangea Reptile, and front-opening glass terrariums from Exo-Terra. These are all great examples of improvements to the standard of captive reptile care. But overall the hobby standards seem to have plateaued. Looking at substrates, instinctual nourishment, provision of live plants to herbivores or omnivores, maintaining tunnels and burrows, and other basic yet important aspects of reptile husbandry, it is clear that these areas have gone all but completely untouched.

The term “bioactive” was coined back in the mid 1990’s. Some poison dart frogs were housed utilizing springtails and isopods in the Atlanta Botanical Gardens (ABG) mix with leaf litter and other organic matter mixed in to provide a self-cleaning, self-maintaining ecosystem within the animals’ enclosure. Since then, it has been very hard for hobbyists to replicate the same results for different biomes, such as temperate forests, deciduous forests, plains, desert, and even different types of neo-tropical habitats. Well, it used to be hard. With bioactive enclosures increasing in popularity, we have a better idea of what we’re doing, and with help from ready-made products like The Bio Dude, building your own bioactive terrarium can be downright easy!

How to Build Your Own Bioactive Terrarium

Keeping reptiles in a 100% organic, self-cleaning, self-maintaining setup will allow you to closely replicate their natural environment and ecological niche, which in turn nurtures the natural instincts and behaviors which make these animals so fascinating to begin with. Another great benefit to bioactive is the financial savings. While you may spend more upfront, long term you save a significant amount of money and time from not constantly having to replace substrates and terrarium accents. Ideally, this one-and-done deal will sustain itself for the entire life of the animal, as long as it is maintained appropriately.

When choosing to go bioactive, there are many ways to get started. But first you will need a solid understanding of your pet reptile’s husbandry needs — its natural habitat, its diet, heating, lighting, humidity, etc. This is where your options become available, and where the fun begins!

After selecting an appropriately-sized enclosure (remember: bigger is always better!), figuring out what type of substrate to use is the next step. If you prefer to use your own, handmade mixes, it is very important to understand how well the soil drains, aerates, and if you are going to need a drainage layer. If you do not want to create your own mixes, the Bio Dude offers a full range of pre-made bioactive substrates to cater to the needs of each biome while taking the needs and instinctual niches of the inhabitants into consideration. (Those will be talked about more in-depth later.)


The drainage layer is the very first step when constructing a tropical or neo-tropical bioactive terrarium and can be composed of many different types of material: pebble rocks, clay pebbles (LECA), or growstone. If you are looking for a drainage layer that is very light, 100% natural with no glass that fully aerates and drains, I recommend HydroGrow by The Bio Dude.

The point of the drainage layer is to catch any and all excess draining water out of the substrate to prevent oversaturation. Oversaturation will quickly ruin and kill your terrarium. Oversaturation will cause a buildup anaerobic bacteria (bad) which will outcompete the aerobic (good) bacteria causing a pH imbalance, soggy soil, root rot, and a potential buildup of toxic methane byproduct in your terrarium.

When maintained appropriately, your substrate will take on water, but excess water will fall through and sit directly into the bottom of the drainage layer. As long as the water line does not exceed the drainage layer into the substrate, the proper soil should maintain, cycle, and flourish for the life of the animal. If the water level gets too close to the substrate, simply siphon out the excess water.

A screen on top of the drainage layer can help to separate out of the soil and drainage layer, although with HydroGrow that is not necessary.  If you are using an alternative drainage material, it is highly recommended to use a screen to prevent the soil from mixing with the drainage layer.


Your soil layer will be placed on top of your drainage layer (if a drainage layer was required), and if a drainage layer was not needed, by placing the soil directly into the terrarium. Soil ingredients such as coco coir, peat moss, sand, charcoal, orchid bark, sphagnum moss, and other things can all be used and mixed to your liking, but it is very important to make sure that the soil is aligned with your reptile’s humidity and biome requirements. Poor soil consistency will quickly kill the terrarium and can even cause damage or death to the inhabitant.

(It’s important to note here that peat moss is a very environmentally unsustainable material, and not recommended to be used when alternatives are available. Coconut fiber/coco coir is one such alternative.)

If you don’t want to create your own mix, the ABG mix we mentioned earlier is a great tool for very high humidity terrariums, but that too will eventually break down into a very large orchid-based substrate over time. So The Bio Dude offers different substrate mixes appropriate for different biomes. Pertaining to reptiles, we have Terra Flora for high humidity environments (Halmahera blue tongue skinks), Terra Fauna for neotropical species (crested geckos, day geckos), Terra Firma for all temperate, deciduous, or burrowing species (ball pythons, corn snakes, tegus), and Terra Sahara for all desert species (such as bearded dragons).

Whether you create your own mix, use The Bio Dude’s mix, or a mix from another vendor, you will need to apply at least a 2.5” substrate depth layer for tropical or neo-tropical and at least a 4”-8” depth for all desert and deciduous/temperate forest species. It is imperative to provide such a deep layer, as many of these species are burrowers by nature and will quickly create a network of tunnels or burrows that they would naturally create in the wild. For species that typically inhabit other animals’ burrows rather than creating their own, you can sculpt burrows for them to use in this layer. Terra Firma and Terra Sahara in particular are specifically formulated to retain all tunnels, burrows, and hides that your animals naturally create, further nurturing their natural wild animal instincts.

Furthermore, a deep, dense substrate layer retains the air pockets necessary to aerate appropriately. This enables the creations of humidity pockets in which your reptile can easily rehydrate, shed, and access clean, fresh air in their terrarium.

Biodegradables & Your Clean-Up Crew

It is very important to mix biodegradables into your substrate. Biodegradables break down over time to create organic nutrients for your soil and plants so the biome is constantly revitalized via natural, organic processes. These essential biodegradables are broken down via two primary mechanisms:

The first way is by tiny organisms that live in almost every ecosystem on the planet: springtails (woodlice) and isopods (rollie pollies). These important invertebrates break down wood, feces, shed, leaf litter, dead plants, and other organic matter, transforming it into vital nutrients that enrich your soil. They also play a pivotal part in aerating the soil.

Another way — which is the primary method that I use in my bioactive kits — is a combination of several different types of fungi, mycorrhizae, and archaea bacteria. These are the backbone for proper change and development in many ecosystems. These organisms break down organic matter on all levels of the terrarium via molds, slimes, mushrooms and other processes. As these microscopic processes break down matter, they create nitrogen and other important organic compounds that can be then absorbed and used by plant roots. Like the springtails and isopods, these processes also aid in the breakdown of shed, feces, dead plants, leaf litter, woods, and mosses, slowly creating your own bioactive ecosystem over time. You can get a starter culture of these organisms with the Bio Shot in The Bio Dude’s store.

You can find assorted biodegradeables like sphagnum moss, leaf litter, and pieces of bark at The Bio Dude’s store or you can collect them yourself. If collecting your own, make sure to get them from a clean, pesticide- and herbicide-free area. Remember, whatever you put into your terrarium will stay in your terrarium since it’s a closed system.

Live Plants

Another benefit of a bioactive terrarium is allowing the keeper to add live plants to the enclosure. Not only do many reptiles seem to prefer having live plants in the terrarium (as opposed to artificial ones), but it also provides several unique benefits for them. When keeping herbivores and omnivores on bioactive, it allows the keeper to purchase healthy edibles, such as herbs or spineless cacti that the animal can graze on at will. Not only does this nurture their natural instincts, it allows them to act like the wild animals that they are. Many reptiles will utilize the live plants as a hiding place (chameleons hiding in live trees, for example) to help them feel more secure. While the live plants improve the air quality in the terrarium, many of them will also hold excess water in the roots, axils, or on the leaves, giving your reptiles a natural place to drink.

Bioactive is the Best Way to Keep Reptiles

When looking at pet reptiles as a whole, some keepers fail because they are not tending to the Big Three of reptile husbandry: proper shedding, respiration, and hydration. But it’s especially important to remember this one thing: you should strive to provide the best care — not just basic care — using research-driven practices and techniques. And when you provide a well set up bioactive environment, it becomes very easy to provide perfect care and husbandry for your pet(s). Providing all the essential elements of care will not only give your reptile a full life, but allow them to act like the wild animals they are by nurturing the same instincts which make them so wonderfully unique.

About the author: Since the age of 13, Josh Halter has had a passion for making his pets’ enclosures emulate their natural habitat as closely as possible. Decades later, this passion evolved into The Bio Dude. With a retail location in Houston, TX, USA, and shipping all over the country, this store makes planning and building beautiful, functional bioactive enclosures easy for anyone who wants to give it a try. For more tips on building bioactive terrariums, visit his blog!


  1. Yes. The moist hide should be in the middle of the enclosure to allow for diversity in hide options. It’s normal for humidity to be higher on the cool side than the warm side, as heat and relative humidity have an inverse relationship.

  2. Just to clarify for leopard geckos – one side of the tank is a hot side, one is a cool side, both with hides and a moist hide closer to the hot side? I notice the humidity spikes on the cool side a lot.

  3. This article was written by Josh Halter (The Bio Dude), so this piece was written with their interests in mind. However, ReptiFiles does have other articles on the topic of starting a bioactive enclosure that go more into detail, which is what I think you might be looking for. You can find a list of those articles in our Blog Archive: https://reptifiles.com/reptile-articles. I also recently wrote an article for the Bio Dude’s blog on the topic of mixing your own substrate, which can be found here: https://www.thebiodude.com/blogs/how-do-i-create-a-bioactive-vivarium/the-pros-cons-of-commercial-vs-diy-bioactive-substrates.

  4. Honestly, I think this is a good guide but is lacking in true information on making your own mixes. I have been making my own bioactive substrates, for a while. I do think that the biodude overprices their stuff, although it is very good and I am a little disappointed that all this guide does to noobies is point them in the direction of the biodude when it should be encouraged that they try their own and make it as comprehensive and easy for them to do that. I think it is just lacking a bit is all I would say.

  5. This was a very interesting article. I’m starting a bioactive terrarium for my classroom and I am doing my research so I can give my pet the best set up possible. I am planning on getting an Anole, do you think you can help me with the type of soil I should get from your The Bio Dude website? Thank you

  6. Unfortunately mixing species is always risky, as there is potential for diseases to hop from reptile to reptile, amphibian to amphibian, etc. A potential exception is millipedes, which can function as CUC. This becomes even more risky if you want to keep the enclosure on the small side, as it gives the occupants very little space to escape from one another. If you want an enclosure no larger than 30 gals, I recommend sticking with only one species. 2 mourning geckos, 3 dart frogs, or 2 tree frogs. The others should be housed singly, and I recommend sticking to a smaller species of garter snake at that size.

  7. I want to have a bioactive vivarium and I’m trying to figure out what species I want. Mourning geckos, green anoles, dart frogs, tree frogs, green snakes, and millipedes I’ve seen are great for bioactive tanks. I want a mix of some of these(plus cleaner crew) but I don’t want the tank to be bigger than 30 gallons. What animals and how many do you recommend for this?

  8. It’s a good idea to keep things as diverse as possible when it comes to your CUC. For a corn snake, I’d recommend at very least powder orange isopods (Porcellionides pruinosus) and springtails. You can also add superworms, a millipede or two, earthworms, and other varieties of isopod. I recommend staying away from the particularly expensive varieties if you’re on a budget, since those are more for collectors than using as CUC.

  9. What clean up crew would you recommend for a simple corn snake bioactive enclosure? I see a lot of people using spring tails and ispods. But there’s a lot of morphs of ispods. Does it matter what you get? (white drawf or the regular brown isopods)

  10. Thanks for informing me! For some reason I thought that sphagnum peat moss was a different, more eco-friendly material than “real” peat moss, but I see now that the two are the same. I will make a note!

  11. Ahhhh she recommended peat moss!!

    This is an awesome how to guide for setting up bioactive enclosures. Great work Mariah 😀.

    The only thing I don’t agree with is recommending peat moss in the soil. I would recommend using sphagnum moss instead as it is more sustainability sourced.

    Peat moss is essentially dead sphagnum moss which settles at the bottom of bogs but to obtain it for our use means digging up bogs, which destroys the potential for regeneration of the swamp and destroys ecosystems.

    Please use sphagnum moss and choose peat moss free pre-mixes where possible. Again, Thanks Mariah for such a helpful guide.

  12. This is excellent informations. Colin Mims, the BioDude has some specific kits and starters for Leopard Geckos, so that’s worth looking at as well.

  13. Absolutely! “Bioactive” does not necessarily mean lush and tropical. And loose substrate is no more dangerous to leopard geckos than it is to other species as long as the gecko is healthy and has access to water and a correct temperature gradient. The Bio Dude actually offers a leopard gecko bioactive kit using his Terra Sahara substrate here: https://www.thebiodude.com/products/leopard-gecko-bioactive-kit.

  14. Can leopard geckos be kept in a bio active set up