This is going to be a “getting started” overview for bioactivity, appropriate custodians, plants, and bioactive husbandry moving forward.
Note: I always opt for “best care, not basic care” but that does not imply bioactive husbandry is required. Enrichment, proper lighting, climbing and burrowing opportunities, multiple gradients, and spacious and hygienic cages, are all required. Bioactivity is a stylistic choice for the keeper; it is not the only way to achieve high quality husbandry. That said, I am a huge fan of bioactivity and it is the route I choose to achieve my husbandry standards.
Terminology / Materials
Drainage Layer/False Bottom: this is the first layer to go in the cage. It allows excess water from the substrate to drain out of the substrate and collect here. Once there, the water can be removed by the keeper via a pre-installed drain (that’s what I have) or a turkey baster. Or you can leave it to evaporate as the substrate above it dries. It all depends on how much you water. If you will be using live plants (not required, but recommended) I would recommend having a drainage layer. If not, and you’re very careful about how much you mist and monitor the soil moisture levels, you may be safe without a drainage layer.
Drainage layer media and screen: lots of things will work as drainage media. Gravel, river rock, lava rock, lightweight drainage layer media “LDL” or “Growstones” (this is what I used, it is quite light and I like it), expanded clay balls/pebbles or “lyca”, or even a platform made of light diffuser egg crate panels. It needs to be around 0.05 meters (0.2 feet) thick. The screen then goes on top to keep the substrate above the drainage layer. I used weed barrier cloth (just perforrated plastic sheet) but fiberglass window screen works too. Don’t use metal screen, it will rust.
Substrate: this is the most needlessly intimidating part of bioactive husbandry. There are 5 components you should have, and they all have lots of suitable substitutions, and exact proportions aren’t that important.
1. Dirt. This can be potting soil, dirt from outside, top soil, whatever. This is the bulk of your substrate.
2. Sand. This helps hold burrow structure and with drainage. Lots of potting soil mixes (especially cacti/succulent mixes) will have sand already, but you can also add plain sand.
3. Fibrous plant material. This holds moisture and helps stabilize humidity. Sphagnum moss is great, but something like coconut fiber works too.
4. Woody plant material. This adds varied texture to the mix, is an important breeding, feeding, and hiding ground for small custodians, holds burrows, and holds air pockets in the soil. Orchid bark is popular, charcoal is good (especially for springtails), I also toss in whatever I cut off of larger furnishings.
To be honest, I tend to buy several bags of different pre-made mixes. My substrate has reptile branded bio substrate, cacti potting mix, orchid potting mix, top soil, lava rock, charcoal, and chunks of wood and cork that I cut off of the larger furnishings. Obviously aim for organic mixes and avoid anything that mentions weed or pest repellant.
5. The last ingredient is leaf litter. This is fuel for the custodians and can include dried leaves (oak and magnolia are especially popular), rotting hardwoods, seed pods, pine cones, etc etc.
1. Prepare the cage. Ensure it is waterproof, at least the area the substrate will be touching. HEAT MUST COME FROM ABOVE. No UTHs or heat tape with bioactive enclosures (really you shouldn’t use those anyways). The custodians will instinctively burrow to escape the heat of the day, and if the heat is coming from below, they may kill themselves; but certainly they will not clean that section of soil.
*Optional* If you want to use a drain, it needs to go in first. I just drilled a 1/4″ hole and siliconed in a piece of 1/4″ airline tubing which runs into the sump (my cage is a palidarium, you can use use a bucket or install a valve to drain as needed).
2. Wash the drainage media. You don’t want the dust from the media making mud in the cage, especially if using LDL (it’s recycled glass, glass dust is no fun). I drilled holes in a bucket and ran water over the media until the water drained out clear.
3. Drainage media goes down in a 2″ layer. Screen goes on top. Ensure the screen curls up the sides an inch or 2, this is to make sure all the substrate is kept separate. If the substrate gets into the drainage, it can start to rot.
4. Substrate goes in. You want 4″ of substrate depth at least, but more is better.
Springtails and isopods are the backbone of any relatively humid bioactive environment. Go for “temperate springtails”, though you can likely maintain tropical varieties as well. For isopods, I have had great success with dwarf whites, powder blues, and giant canyons. I have probably a dozen species though, with good environmental gradation you can support lots of different invertebrates.
Part of the fun of bioactive husbandry though is collecting all sorts of interesting custodians. Millipedes, roaches, beetles, and some others can cohabit successfully with your P.regius. The bigger the cage, the more bugs you can enjoy.
Worms are another good option. Earth worms will really help your plants thrive.
Using plants is not required for bioactivity, but it is helpful. They help regulate humidity, offer sensory enrichment, offer gradation in lighting and security, and uptake liquid wastes. Just about anything that vines in the house plant section of your gardening center will work. Upright plants need to be sturdy and resilient; they will be trampled. Pothos is a great place to start. Starting with larger plants will give them a better chance of survival, as well as letting them root for a few weeks before adding the snake.
Once this is all setup, you don’t just get to ignore cleaning. You still need to spot clean as you normally would. Over time however, you will notice less and less waste as the custodians will be handling it before you see it. I’ve seen full sheds dissappear overnight. If you get to a place where you don’t have to clean, cool. If not, you’re still doing bioactive husbandry because your soil is healthy, oxygenated, and clean after spot cleaning and without full replacement.
The custodians will grow to the availability of food. How fast waste disappears is a function of custodian population. So, if you want them to clean faster, you need to feed them in between waste production by the snake. Veggies, leaves, rotting hardwoods, fish flakes, bee pollen, even left over reptile food can be fed to the cage if you so choose. Cuttlebone is also a good idea to help them molt.
Water Cycle and Bacteria
What sort of issues do you need to look out for with bioactive husbandry? The main issues to look out for are compacted soil, overly wet soil, and overly dry or dusty soil. Oxygen must flow to all areas of the cage, but particularly the soil. The water cycle in the cage achieves this. If the soil gets compacted, water cannot flow through it. If the soil is too wet, water is not draining through. If it’s too dry, then water isn’t getting to it. All of these are signs that the water cycle is being interrupted somehow.
When water flow stops, oxygen flow stops, and aerobic bacteria are replaced with anaerobic bacteria. Aerobic bacteria are preferable because the waste products of aerobic cellular respiration are H2O and CO2. These are both in turn used by plants to produce O2, but even if plants are not present, these waste compounds are harmless. Anaerobic cellular respiration however produces compounds that can alter pH and eventually become toxic in large quantities. In a rotting situation (no O2 and very high organic matter), fermentation may even take place, which produces really nasty waste compounds.
If this happens, you will smell an ammonia-like odor. It’s pretty foul. The first things to suffer will be the beneficial bacteria, then the custodians and plants. The reptile will usually be safe unless the issue is allowed to get particularly bad. Luckily, the solution is simply replacing the fouled soil and restoring water flow to the area. Aerobic respiration is much more efficient than anaerobic, so if oxygen is present, aerobic bacteria will out compete all others. Or for those that can do both, they will choose aerobic.