Basic Bioactive Set-ups

Basic Bio-active Set-ups

There seems to be a real mystique in the minds of many modern reptile and amphibian keepers on the subject of bio-active systems; they are often thought to be ‘new-fangled’, ‘complicated’ or ‘difficult’. In reality, they are just a return to an old-fashioned kind of keeping- they didn’t always have a fancy name, but they were, on the whole, the way it was done. The basic idea is that our reps’ and ‘phibs didn’t evolve on paper towelling or sterile bedding; they benefit from living in more ‘natural’ surroundings, in ecosystems where wastes are recycled into plant nutrients, and nothing is wasted. To a large extent, such a system should be self-regulating and self-cleaning, whilst providing a home where animals can demonstrate their natural behaviours. In truth, of course, even an enclosure set up in this way is not truly ‘natural’- we aren’t including any of our animal’s predators, for a start- but as a compromise, it can work very well.

Getting started

The first thing to bear in mind with any bioactive system is the normal habitat of the animal in question. Most of my experience is with reps’ and ‘phibs from relatively damp environments, so that is what I will mainly concentrate on in this piece, although the basic methods can be adapted toward drier habitats as needed. I have used the technique successfully with drier woodland animals such as corn snakes, and with savannah species including barrel skinks and plated lizards- in both cases, so long as the animals have a choice of damper and drier areas, the method works well.

While many of the plants we use in vivaria need frequent watering, what they don’t need is for their roots to be permanently wet, or to sit in stagnant water. A soil without drainage will become soggy and anaerobic , causing roots to rot, and eventually killing the plant. The drainage layer, then, is the first consideration.

Several materials can be used for this layer; they should be fairly large-particle, to allow water to drain through freely, and inert, so that they don’t add unwanted chemicals to the water. I have used large-particle gravel successfully, and have seen filter aggregate used as well, but my personal favourite is ‘leca’, an expanded clay aggregate sold under various brand names. This has the appearance of little brown pebbles and is used extensively in horticulture, especially in hydroponics. It has a couple of advantages over the other materials; for one it is relatively light- a real consideration in bigger vivaria, whose overall weight will already be high. It also absorbs and holds a certain amount of water, releasing it slowly back into the tank, so keeping humidity stable. Leca can be bought online, from some garden centres and some pet retailers, as well as from shops specialising in hydroponic supplies. Whichever material you use, aim for a layer at least one or two inches in depth- deeper in very large vivs, covering the entire base.

The next step is to add a barrier between the drainage layer and the soil. This should allow water to drain freely through, while preventing the soil from being washed down into the aggregate. Many people find weed mat available from any garden centre useful; I find plain old nylon net curtain works just as well, and off-cuts are available for pennies.

Now, the soil. There are many, many, (many, many!) formulae and recipes for this, some involving ground tree fern bark and even more exotic components; again, I will detail what I use- like many things in this hobby, this is only my method, not The Law!

My preferred mix is based on a combination of ‘live’ leaf-mould, collected from a mixed beech and sweet chestnut wood, high on the North Downs, away from roads, industry and ponds. The ‘pond’ element is quite important; there are very few reptile pathogens native to the UK, but some amphibian diseases, including the dreaded ‘red-leg’ are endemic- I don’t usually collect materials near water.

To this I add orchid bark, coco fibre (Eco Earth, etc) and organic potting soil- proportions vary depending on what I have handy and what is going into the viv, but the aim is for a fairly open, moisture-retaining but free-draining mix. Again, the depth will vary according to what animals and plants will be going into the enclosure. The leaf-mould has a full component of invertebrates (including native woodlice and springtails), bacteria and fungi devoted to breaking down waste; to this I usually add tropical woodlice, springtails and compost worms- which tolerate higher viv temperatures better than earthworms, and are brilliant at breaking down dung. I find that only a few worms are needed. The resulting ‘mixed’ ecology is doubtless somewhat strange, but it works!

Finally, the fun part; landscaping and planting. I usually collect nice pieces of wood and leaf-litter along with my leaf-mould; they look good in the vivs and add to the ‘natural’ set-up. I don’t usually treat them in any way; any hitchhikers will either add to the clean-up crew or become extra food for the animals. I should add one note of caution, though; a friend of mine who specialises in dart frogs warns of the dangers of nemerteans- a kind of flat worm that preys on springtails- essential food for small darts, often found on fallen leaves, and spiders- a tiny baby spider could potentially grow to a size that could threaten a small frog. Neither are really a consideration in my set-ups, but I felt it was important to pass the concerns on. It is perfectly possible, should this be a concern, to ‘nuke’ your materials in the microwave for a couple of minutes, but that means you lose out on the useful native organisms.

Plants will vary depending on the environment you are attempting to recreate, and safe plants etc are covered elsewhere, so I shan’t say too much on them here, except to warn that most plants available from florists, garden centres and supermarkets will have been treated with various pesticides and fertilisers, which could be dangerous to your animals. I recommend that new plants are rinsed thoroughly, including the roots, and re-potted in organic compost. It is then a good idea to ‘rest’ them for a few weeks, watering liberally,

before use. This is because some of the chemicals used are systemic, which means that they are designed to be absorbed by the plant and distributed throughout its systems. They will be flushed out over time, though.

To de-pot or not to de-pot? That depends on you. Plants kept in pots will obviously not get the full benefit of the nutrients available in the soil, but in some individual cases, there is a case for keeping them potted. Palms, for example, tend to do better with restricted root run and minimal root disturbance, while plants that potentially grow very big (Monstera, Dracaena) may eventually outgrow the space and have to be hoiked out and replaced. This is much easier to do without wrecking the whole tank if they are contained.

Conclusion

I hope this short piece demystifies and explains some of the ‘how to’s of bioactive set-ups as well as some of the ‘why’s. Once the basic system is made, I find them infinitely easier to maintain than ‘sterile’ arrangements; cleaning is minimal, mostly consisting of wiping down the glass; the rest of maintenance mostly involves cutting back over-enthusiastic plants, replacing those plants that turn out not to do well, and occasionally topping up the leaf-litter. Oh, and they look quite good, too!

Copyright 2014 Ron Eddy