What is a long-term CO2 indicator for?
A long-term CO2 indicator is a small clear plastic container which contains a reagent that changes colour according to the pH and KH of the water. It is attached to the inside glass of the aquarium using a small sucker. Although arguably less precise than a set of test kits, it provides a visual indication to warn you if you’re adding too much (or too little) CO2. This article was first published in the November 2002 issue of Practical Fishkeeping.
