Water is never lost from a sealed biosphere. It just changes state. If you see heavy condensation on the glass in the morning, that is normal. If you see it constantly, you have too much water.

| Component | Purpose | |-----------|---------| | Clear glass or PET plastic bottle (1–2 L) | Container; glass preferred for scratch resistance | | Natural pond water or dechlorinated tap water | Aquatic biosphere base | | Pond sediment / garden soil (sterilized optional) | Nutrient source and microbial inoculum | | Aquatic plants (e.g., Elodea , Ceratophyllum ) | Oxygen production, habitat | | Small aquatic snails or Daphnia | Grazer / consumer | | Springtails / small earthworms | Terrestrial decomposition | | Activated charcoal (optional) | Filters toxins, reduces odors | | Cheesecloth + rubber band | Initial aeration if building semi-closed | | Light source (LED grow light or indirect sunlight) | Energy input | | Magnifying glass / USB microscope | Observation | | Notebook, camera | Data recording |

If sealed, never open for more than 10 minutes per month unless correcting an imbalance.