ISTA Co2 Glass Indicator

The ISTA Co2 Glass Indicator is a CO2 system component for planted aquariums.

Key Features

• Essential for providing carbon dioxide to aquatic plants
• Promotes healthy and vigorous plant growth
• Compatible with standard CO2 regulator setups

The ISTA CO2 Glass Indicator for Planted Tanks

This glass indicator, often called a drop checker, is the simplest way to read how much CO2 is actually dissolved in your planted tank. Filled with an indicator solution, it changes colour to show whether your CO2 level is low, in the ideal range, or heading too high. We consider it essential kit, because counting bubbles alone tells you the injection rate, not what the plants and fish are really experiencing in the water.

The glass body suits aquascaped tanks where appearance counts, sitting discreetly in a back corner. In our warm 27-29C water, CO2 saturation and pH shift through the day, so the indicator gives you a visual cue to adjust before fish show stress at lights-on. It typically reads on a slight delay, so make changes gradually and check again after an hour or two.

Use a proper 4dKH reference solution for accurate colour readings rather than tank water. Browse the full CO2 systems range, and read our drop checker guide, indicator solution guide, and CO2 measurement guide.