Closed Ecosystems on terrariums
What's Happening
Closed ecosystems (fully sealed terrariums) aim to replicate Earth's biosphere at miniature scale, balancing photosynthesis (oxygen production) and respiration (oxygen consumption). Successful systems require: (1) Producers (plants) generating oxygen through photosynthesis exceeding their own respiration needs, (2) Decomposers (soil bacteria, fungi) breaking down organic matter and recycling nutrients, (3) Consumers (optional microfauna like springtails) controlling mold and debris. The critical balance depends on plant biomass-to-container volume ratio—too many plants deplete CO2; too few cannot maintain oxygen levels for soil microbiome health.
How to Fix It
- 1
Seal only when condensation patterns stabilize—visible droplets in morning, clearing by afternoon
- 2
If sealed system shows mold: open immediately, remove affected material, improve airflow for 1 week before resealing
- 3
Monitor plant vigor: yellowing indicates nitrogen limitation from incomplete decomposition cycle
- 4
Add springtails (Collembola) if white mold develops—they consume fungal hyphae without harming plants
- 5
Replace container if algae blooms on glass—indicates excessive light or nutrients
How to Prevent It
Calculate plant load: 1 liter container volume supports approximately 15-25 square inches of leaf surface area. Include fast-growing oxygenators (baby tears, moss, small ferns) alongside slower species. Use sterilized potting mix with living soil inoculant to establish healthy decomposer populations. Allow 2-3 week open-cycle period before sealing to establish microbial balance.