ISTA CO2 Indicator

A drop-checker indicator solution that shows your aquarium’s dissolved CO2 level at a glance — turning blue (low), green (ideal) or yellow (high) so you can dial in CO2 injection for healthy plant growth.

Using the ISTA CO2 Indicator in Singapore Planted Tanks

In our experience running high-tech scapes locally, a drop-checker filled with this ISTA solution is the most honest gauge of dissolved CO2 you can keep in the tank. We position it diagonally opposite the diffuser so the reading reflects what plants at the far end actually receive, not just the bubble curtain. Give the colour an hour or two to settle after any change; the reaction lags behind the water, so chasing instant green leads to overshooting.

Singapore tap water is soft and slightly acidic, which shifts how the green endpoint reads, so we treat colour as a trend rather than an exact ppm. Pair it with a morning pH check for a fuller picture. On warm 28C days CO2 holds less readily and demand climbs, so livestock-heavy tanks should aim for the lighter end of green and watch fish for surface gasping before lights-on.

Refill solution and matching glassware sit in our products range. For setting a baseline read our CO2 measurement guide, and beginners deciding on injection should start with whether your tank needs CO2.