Testing water – here’s how

The water in your aquarium is outstandingly significant because it is a life-giving element for fish and plants. The water and its quality influences the fish and plants living inside, while conversely the life processes of these fish and plants also influence the water quality. Ideally water looks crystal-clear, but this also means that any toxic substances and minerals inside cannot be seen. That’s why the monitoring of the most important water values (more about that under Keeping an eye on the most important water values ) with water tests is a real must. We will help you to make the invisible components visible.

Not even tap water, which is actually a foodstuff in Germany, is always suitable for fish without additional treatment, since the required bacteria are missing and the parameters possibly don’t meet the requirements of your animals.

By testing the water you will receive valuable background knowledge about that and you have the possibility to choose the right course of action. The water test is not only required when problems in the aquarium arise, it should be an integral part of the aquarium routine.

That’s why we would like to tell you about water testing and show how easy it is.

Here’s how testing works

  • Be sure to rinse the cuvettes several times in the water you want to test.
  • Please follow the instructions and differentiate between the small and large spoon end when adding a powder (nitrate test large spoon end, phosphate test small spoon end).
  • Please also differentiate between swivelling and shaking the cuvette in accordance with the instructions.
  • ALWAYS keep the reagent bottles in a vertical position when adding drops. The drop size changes when holding the bottle in an inclined or in horizontal position.

With the drop tests for aquariums we distinguish between three different types which we will explain in detail to you below:


During the colour comparison test (colorimetric test) please follow the instructions closely and add the prescribed number of drops of one or several reagents into the prescribed amount of water of the cuvette. This results in colouring which is then compared to a colour chart and shows you how much of the substance is present in the water. This same principle is used in the JBL pH Test 3.0-10.0 , JBL pH Test 6.0-7.6 , JBL pH Test 7.4-9.0 , JBL Mg Magnesium Test Set Freshwater , JBL Iron Test Fe , JBL Phosphate Test sensitive , JBL Phosphate Test Kit PO₄ for koi , JBL Oxygen Test O₂ , JBL Silicate Test SiO₂ , JBL Copper Test Cu , JBL Ammonium Test NH₄ , JBL Nitrate Test NO₃ and JBL Nitrite Test NO₂ . What makes the JBL colour comparison tests special is that you fill a second cuvette at the same time with sample water and put it on the colour chart with the colour field. If you now look from above through your water sample onto the colour field, the printed colour changes due to the inherent water colouring which then is taken into account in the result. This JBL comparator system facilitates the colour comparison for you and has laboratory-standard precision.


In the turbidimetric test you add indicators into your clear water sample to create turbidity. Add this “cloudy” water millilitre after millilitre into the special test tube until a cross on the underlying colour chart is no longer recognisable because of the increasing layer of cloudy water inside the test tube. That’s how the JBL K Potassium Test Set works. Although during the JBL oxygen test turbidity arises too, you still need to compare the colouring with a colour comparison chart at the end.


In the drop counting test (which is called titration) you count from the first added drop of the reagent the number of drops until the colour changes into another defined colour. At the JBL GH Test this would be from red to green, in the JBL KH Test , in the JBL CO₂ Direct Test Set from colourless to pink and in the JBL Magnesium/Calcium Test from red to green or red to blue.

Finally, it must be mentioned that there is another method to determine the water values, the test strips ( JBL EasyTest 6in1 ) . With them you can monitor up to seven water parameters in one go and display them in an overview. A special opportunity for that is offered by the JBL ProScan which can deliver precise measurement results after 60 seconds via smartphone and which offers a much finer scaling than conventional test strips on the market.

How you test is your choice. Keep an eye on the water values!

© 28.09.2016
Matthias Wiesensee
Matthias Wiesensee
M.Sc. Wirtschaftsinformatik
JBL GmbH & Co. KG

Social Media, Online Marketing, Homepage, Kundenservice, Problemlöser, Fotografie, Blogger, Tauchen, Inlineskating, Aquaristik, Gartenteich, Reisen, Technik, Elektronische Musik