Does bioactive substrate have to have a drainage layer? I feel like if there are no live plants that need to be watered, moist substrate with a cleanup crew of springtails and isopods should be fine, right? This is for a juvenile leachie bin with a mix of peat moss and coco coir and layer of leaf litter
As long as you don’t have plants in there it doesn’t really need a drainage layer.
Some people may disagree; there are various systems and opinions on bioactive, just like other animal keeping subjects.
Many people don’t use them for arid bioactives either, as long as they’re using the proper substrate mix, even with plants.
I don’t have them in any of my bug bioactives, or even my crestie bioactive, as they’re not planted. I am not planning on one in my leopard gecko’s bioactive, either.
I do, however, have it in my heavily planted tropical bioactives.
The substrate will wick moisture from a drainage layer and stay evenly moist, which is ideal for high-humidity setups. It is not good for arid setups, however, as you want moist microclimates and drier areas.
It is definitely perfect for tropical, humid, planted vivs, because it allows the plants to get the moisture they need without getting too soggy. Most of my vivs have plants that have shot their roots down the edges into the drainage layer, as well.
If you don’t have a drainage layer, you may have just a bit more upkeep. Without a drainage layer in a setup for a higher humidity animal such as a leachie, you’ll likely need to do some substrate stirring from time to time to keep it at the right moisture level. You don’t want to disturb the mycelium (fungus) too much, as it is part of a healthy decomposition web in your setup, or hurt your CUC, so there’s a balance that must be maintained.
Peat and coco fiber alone is not an ideal substrate for a bioactive. It is better to have a mix of substrate particle sizes, which will allow beneficial bacteria and mycelium to grow, keep the mix more aerated, and allow a healthy environment for the clean up crew. If you wish to mix your own, here’s a suggested recipe for a humid tropical or subtropical viv:
2 parts Ground Tree Fern Root (also called bark)
2 parts Fine Orchid/Fir Bark
1 part Peat Moss
1 part Milled Sphagnum Moss (not long-fiber)
1-2 parts Fine Horticultural Charcoal
There are many other recipes online, using coco fiber, and so on. NEHerp’s substrate is a good choice which uses coco fiber, if you want something pre-mixed!
Then place a layer of leaf litter over that.
For a leachie, that has such messy poop, keep in mind that you will need a strong, diverse, and healthy CUC, and a large area of substrate proportionately to “manage” the waste. Think of it like cycling an aquarium – some fish need a proportionately stronger filter and area because they are high bioload.
CUC do not usually clean anything above substrate level (though I have some giant orange isopods that are quite industrious).