Check solution for CO₂ long-term tests
The DRAK CO₂ long-term test solutions for 20 or 30 mg/l CO₂ can be used in any standard CO₂ long-term test for long-term measurement of the optimum CO₂ concentration. Continuous monitoring of this most important plant nutrient is essential for the well-being and growth of your aquatic plants. Monitoring the CO₂ concentration using a long-term test with our CO₂ long-term test solutions works completely independently of the aquarium water and therefore has the advantage that no substances such as humic acids or phosphates can interfere with or influence the measurement.
Instructions
- Depending on the system, add 1 to 3 ml of the CO₂ permanent test solution to the permanent test
- Place the long-term test in a location with sufficient water movement so that it can be read easily
- After 1 to 2 hours, the equilibrium with the aquarium water has been reached
- The green colour indicates the optimum CO₂ concentration of 20 or 30 mg/l - blue stands for too little, yellow for too much carbon dioxide
How it works
Nature does not like differences in concentration and equalises them through diffusion, among other things. This is why the CO₂ concentration of the test liquid of the long-term test is in equilibrium with the CO₂ concentration of the aquarium water via the air bubble in the long-term test. As diffusion takes time, the reaction of the long-term test lags somewhat behind reality. The test must therefore always be allowed the above-mentioned 1 - 2 hours reaction time after changes.
The pH indicator bromothymol blue is used as the colouring agent for the test solution, which changes from blue (higher pH) to green to yellow (lower pH) at pH 6.6. The pH value of the test solution is influenced by the CO₂ concentration of the water in the aquarium. The carbonate hardness (buffer) of the test solution set during the preparation of the solution is used to determine which pH is set at which CO₂ concentration. This ensures that the solutions turn a light green colour at the desired CO₂ concentrations of 20 or 30 mg/l.
The permanent test is therefore a useful tool for monitoring the level of carbon dioxide, which is essential for aquatic plants, with sufficient accuracy. Optimum growth is not possible without sufficient CO₂.
Notes
Please replace the solution if it fades or changes colour (i.e. not blue, green or yellow). This is due to bacterial degradation of the ingredients. The permanent tests should therefore be kept meticulously clean. We recommend regular cleaning or disinfection every 3 - 6 months by immersing the device in a diluted hydrogen peroxide or hypochlorite solution for a few hours.
A filling should work for at least 2 - 3 weeks, otherwise we would recommend disinfection as soon as possible.
The same applies to the solution in the bottles: Never touch the neck of the bottle with your bare fingers and never pour anything back into the bottle. Do not leave the bottle open for longer than necessary.
Use disposable pipettes or syringes with needles for filling.
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71101 Schönaich
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2 reviews
3 October 2025 15:27
The check solution does what it should
The Check solution does what it should. I can recommend it.
7 March 2023 12:50
Fits my aquarium
Very good
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