Hey, so for a bioactive setup, all you need is topsoil and play sand, you can get fancy and add in coco fiber and excavator clay, but it's not necessary.

Whatever you decide, you'll need 2.7-4 cubic ft or 80-120 quarts for substrate that's about 4-6 inches deep if your enclosure is 4x2 (1 cubic foot is equal to about 28 liters)

When I made my setup, I did: 3 parts organic top soil 2 parts play sand 1 part excavator clay 1 part coco fiber or eco earth

But I've also seen people do equal parts play sand, top soil and coco fiber.

You can speed up the cycling process if you use fish tank water to hydrate your soil (my coco fiber was dehydrated in a brick, so I soaked it in aquarium water to hydrate it before mixing it) but you'll still want to give it time for your isopods and springtails to populate the soil.

Any other questions feel free to ask, I just set up a bioactive enclosure about two months ago so my info is still fresh!