The Aqua Rebell CO₂ Permanent Test Solution "CO₂ Check - 20 mg per litre" or "30 mg per litre" can be filled into any standard CO₂ permanent test and serves for the long-term monitoring of the CO₂ level in aquariums. An optimal CO₂-supply is essential for the thriving of aquatic plants and should therefore be continuously monitored. The advantage of the CO₂ Permanent Test Solution is that the determination of the CO₂-supply takes place independently of the aquarium water, thus substances such as humic acids cannot affect the CO₂ check.

Available in a 250 ml container.

A pipette for filling the permanent test is included in the delivery.

The permanent test is filled with 1 - 2 ml of the CO₂ Permanent Test Solution and then positioned in a well-circulated area in the aquarium. After about 1 - 2 hours, the CO₂ content of the aquarium water can be read. A green colour indicates an optimal CO₂-supply of approximately 20 mg/l or 30 mg/l.

A CO₂ permanent test is very useful in an aquarium. Often, aquatic plants lack the essential CO₂, preventing optimal growth. With a CO₂ permanent test, the CO₂ level can be controlled with sufficient accuracy. The dye bromothymol blue used has the property of changing colour in a defined pH range.

CO₂ diffuses from the aquarium water through the air bubble in the permanent test into the test solution and vice versa. Depending on its CO₂ content, the pH value of the test liquid and thus its colour changes. A defined carbonate hardness in the test liquid determines at which CO₂ concentration a certain pH value is established. The test solutions "CO₂ Check 20 mg per litre" and "30 mg per litre" turn light green when their pH value is around 6,6. This is achieved at a CO₂ concentration of 20 mg/l or 30 mg/l. For this reason, the test solution "CO₂ Check 20 mg per litre" or "30 mg per litre" indicates a light green tone at a CO₂ value of the aquarium water of 20 mg/l or 30 mg/l. If the CO₂-supply in the aquarium is less than 20 or 30 mg per litre, the test reagent remains blue; if the CO₂-supply exceeds the mark of 20 or 30 mg per litre, the test reagent turns yellow.