Guide |link|: Bottle Biosphere

This is normal occasionally, but if it's widespread, the system may be too wet. Trim dead leaves to prevent mold.

Screw cap tightly or seal with silicone. (Option: Leave semi-sealed for first week to allow gas equilibrium.) Bottle Biosphere Guide

: Add a thin layer of activated charcoal over the gravel. This helps keep the water clean and prevents unpleasant odors. This is normal occasionally, but if it's widespread,