Exoterra Bio Drain 4.4 lb: 2 kg

Specifications

• Contents: 2 kg / 4.4 lb (PT3115). Exo Terra also make Bio Drain in Nano, Mini, Small and Medium sizes and as a Cut-To-Fit format.
• Material: a natural, inorganic bedrock. It is not a soil and not an organic substrate.
• Behaviour: non-decomposable. Exo Terra are explicit that it will not rot or break down the way organic substrates do, so the drainage layer keeps working instead of collapsing into mud.
• Structure: porous, which is what lets a population of nitrifying bacteria establish in it. Exo Terra describe the layer as functioning as a biological filtration system in its own right.
• Use: the bottom drainage layer of a tropical terrarium, bioactive setup or paludarium.
• Companion item: the Bio Drain Terrarium Draining Mesh, which Exo Terra describe as optional and sell separately. It keeps the drainage layer and the top-layer substrate from mixing.

Its role in a bioactive terrarium is to stop the top layer becoming waterlogged. Exo Terra’s reasoning: over-saturated substrate lets anaerobic bacteria outcompete the beneficial ones, and anaerobic bacteria are what produce the foul smell. Good drainage and aeration keep the moisture gradient that isopods, springtails, earthworms and the rest of the clean-up crew need.

What’s in the Box

One 2 kg / 4.4 lb bag of Bio Drain draining substrate (PT3115). That is all. Exo Terra publish no other contents for this pack.

The mesh is not included. Exo Terra’s own instructions call the Bio Drain Terrarium Draining Mesh optional and it is a separate purchase. Without it the drainage gravel and your top-layer soil will mix over time, which is the failure mode the layer exists to prevent. Their note for a big footprint (the 90 cm terrariums PT2613, PT2614 and PT2609 among them) is to combine multiple pieces of mesh.

Setup & Use

Exo Terra’s own layering procedure, in their order:

1. Stand the terrarium on an even surface and clean the waterproof bottom.
2. Wash the Bio Drain thoroughly and spread it evenly across the base. Do not skip the wash. Fines left in it will cloud the water you are trying to keep clean.
3. Create a water section by removing substrate where you want it.
4. Cover the drainage layer with Bio Drain Mesh, and separate the water section with moss, bark or rocks.
5. Add a biological substrate such as a plantation-soil type on the land area.
6. Plant your live plants, mosses and ferns, then cover the top soil with leaf litter. Exo Terra’s note here is worth reading twice: the plants shelter the clean-up crew and hold moisture, but they also absorb ammonium and nitrate out of the soil.
7. Add an aquatic substrate to the water section and fill it.

• Both the substrate and the mesh are inorganic, so neither rots out from under the setup later.
• The water that collects in the drainage layer can be circulated through a waterfall or a dripping plant rather than sitting still.
• Exo Terra suggest seeding the terrarium water with a beneficial-organism product to bring the biological filtration up to speed faster. They name their own Turtle Clean, PT1998 and PT1999.

How deep to lay it is a judgement call on your footprint and how wet you intend to run the terrarium; Exo Terra publish no depth figure, so we are not quoting one. As a working rule, the layer has to be deep enough that standing water never reaches the soil above it.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number, or email us if you would rather, and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 48 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.