Water Testing Equipment

Water-quality testing is one of the more important jobs in aquaculture and essential for the success of am aquaponics system. If the water quality of a culture system is poor, stock can suffer from health problems such as damage and diseases. A range of tools and test kits are used to test water-quality parameters such as the level of dissolved oxygen, pH, alkalinity, water hardness, ammonia levels and so on.
Click on an item below to find out more about it

Dissolved Oxygen Meter

Image of a dissolved oxygen meter.
Image of a dissolved oxygen meter.


A dissolved oxygen meter is used to measure the level of dissolved oxygen in water. It consists of a probe and a meter. The probe is lowered into water and gently moved from side to side, then a reading is taken from the meter.




Follow these steps to calibrate and use a dissolved oxygen meter:

  1. Turn the meter on and inspect the probe for damage.
  2. Place the probe in a holder that contains a sponge which has been moistened with distilled water.
  3. Allow time for the probe to "warm up" and for the air in the probe holder to become saturated with water vapour.
  4. Set the altitude on the meter.
  5. The probe will now be calibrated to 100% saturation.
  6. Set the salinity of the water sample that you want to measure on the meter.
  7. Put the probe into the water sample and gently move it from side to side.
  8. Wait until the reading on the meter becomes stable, then record the result.

The methods of calibration can be very similar for different types of dissolved oxygen meters, but you should always check the user manual for the specific dissolved oxygen meter you are using for the correct way to calibrate it.





Flat batteries and old or damaged probe membranes need to be replaced.
After using a dissolved oxygen meter:
  1. inspect the probe for signs of damage
  2. rinse the probe with distilled water and place it in the storage holder
  3. turn the meter off and wipe the outside dry with a soft cloth
  4. return the meter to its proper storage area.



pH Meters

Photo of a type of pH meter.
Photo of a type of pH meter.

Photo of a pH meter commonly used by fish farmers.
Photo of a pH meter commonly used by fish farmers.

Two different types of pH meters.




A pH meter is used to measure the pH in water. It consists of a probe and a meter. The probe is lowered into the water sample and the pH of the sample will be displayed on the meter.



Follow these steps to calibrate a pH meter:
  1. Turn the meter on.
  2. Connect the probe to the meter.
  3. Place the probe in //buffer// 7 solution and wait for the reading to stabilise.
  4. Press the "Cal" button to enter the calibrate mode.
  5. Press the "Con" button to set the meter to pH 7.
  6. This method can be repeated for a buffer 4 and/or a buffer 10 solution.
  7. Press the "Meas" button and Measure will appear on the display screen.
  8. Rinse the probe with distilled water.
  9. The pH meter is now calibrated and ready for use.

The methods of calibration are very similar for most pH meters. However, you should always check the user manual for the meter you are using to find out how to calibrate it.




To use the pH meter:
  1. place the probe in the sample to be measured
  2. wait for a stable reading to appear on the meter
  3. record that reading.





Always clean the pH meter after use. Flat batteries and old or damaged probe membranes also need to be replaced.
Follow these steps to clean the pH meter:
  1. Turn the meter off.
  2. Remove the probe from the meter if necessary.
  3. Rinse the probe in distilled water.
  4. Place the probe in storage solution.
  5. Wipe the outside of the meter dry with a soft cloth.

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Salinity

Image of a salinity meter.
Image of a salinity meter.
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A salinity meter is used to measure the salinity of water. A salinity meter has a probe that detects the salinity of a water sample, and a meter that displays the salinity of the water in parts per thousand.




Most salinity meters don't require calibration. However, some salinity meters require the temperature of the water sample to be set on the meter before it can measure the salinity of the water sample.




To use a salinity meter:
  1. insert the probe into the water sample so that the probe is completely submerged
  2. allow time for the reading on the meter to become stable
  3. record the value of the reading on the meter once it stops changing.





Always clean the salinity meter after use. To do this:
  1. turn the meter off
  2. rinse the probe with distilled water
  3. store the probe in the storage chamber
  4. wipe the meter dry with a soft cloth
  5. return the meter to its proper storage area.

Batteries will need to be replaced when they become flat. You will also need to replace the cable or probe when they become worn down or damaged.
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The refractometer

Image of refractometer with eyepiece and prism labelled.
Image of refractometer with eyepiece and prism labelled.



The refractometer is used to measure the salinity of a water sample. It consists of a long tube (like a small telescope) with a prism at one end and an eyepiece at the other. A prism cover plate protects the prism from accidental damage.
You should always calibrate a refractometer before use.
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Follow these steps to calibrate a refractometer:
  1. Open the prism cover plate and put a few drops of distilled water on the surface of the prism.
  2. Close the prism cover plate.
  3. Hold the refractometer up to the light and look through the eyepiece. You will see something like this:
Image of reading on a refractometer scale.
Image of reading on a refractometer scale.

  1. If the boundary line between the light and dark areas is not at 0 on the scale, turn the top adjusting screw so that it crosses the scale at 0.
  2. You've now calibrated the refractometer!




To use a refractometer:
  1. make sure that it has been properly calibrated
  2. wipe the prism dry with a soft cloth
  3. place a few drops of water from the sample to be measured on the prism and close the prism cover plate
  4. hold the refractometer up to the light and look through the eyepiece
  5. read the salinity level where the boundary line between the light and dark areas crosses the scale
  6. record the result.





The prism and cover plate of the refractometer must be cleaned after each use. To do this:
  1. rinse the prism and cover plate with distilled water
  2. wipe the prism, cover plate and the outside of the refractometer dry
  3. place the refractometer in the case and return it to the correct storage area.

To maintain the condition of the refractometer:
  1. clean the eyepiece with lens cleaning tissue
  2. lubricate the hinge of the cover plate so that it doesn't get stuck.





Temperature
Image of thermometer.
Image of thermometer.

A thermometer is used to record the temperature of water. To use it, lower the thermometer into the water and wait a minute or two. Then take the thermometer out and read the temperature recorded on it.



pH Test Kit

Image of pH test kit.
Image of pH test kit.




A pH test kit is used to measure the pH level of a water sample. Generally, an indicator solution is added to a known volume of water sample. This causes the water to change colour.
The colour of the water sample is compared to the range of colours in a chart to determine the pH of water sample tested.




After use, rinse out the sample container. Wipe the container and the test kit dry, then store the pH test kit properly. Check the amount of indicator solution left. You may need to replace the solution if it's running low.




pH test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using pH test kits:
  • Always wear clean gloves when handling chemicals.
  • Always store used solutions in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow indicator solution.
  • Do not sniff the indicator solution.



Image of ammonia testkit.
Image of ammonia testkit.




An ammonia test kit is used to measure the level of ammonia in a water sample. It comes with two separate reagents that are added to the water sample.
To use the ammonia test kit:
  1. fill the container with the water sample
  2. add the first reagent to the water sample
  3. add the second reagent, then wait for the water to change colour
  4. compare the colour of the water sample to the colour chart that comes with the test kit
  5. find the colour on the chart that matches the colour of the water sample, and take a reading of the value on the chart. This is the amount of ammonia in the water sample.





After use, rinse out the container. Wipe the container and the test kit dry, then store the ammonia test kit properly. You may need to replace the reagents if they are running low.



Ammonia test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using an ammonia test kit:
  • Always wear clean gloves when using the test kit.
  • Always store used waste reagents in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow reagents.
  • Do not smell the reagents.



Image of nitrite test kit.
Image of nitrite test kit.




A nitrite test kit is used to measure the amount of nitrite in a water sample. The test kit often comes with two reagents and a sampling container.
To use the nitrite test kit:
  1. fill the container with the water sample
  2. add the first reagent to the water sample
  3. add the second reagent and wait for the sample to change colour
  4. compare the colour of the water sample to the colour chart that comes with the test kit
  5. find the colour on the chart that matches the colour of the water sample, and take a reading of the value on the chart. This is the level of nitrite in the water sample.

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After use, rinse out the container. Wipe the container and the test kit dry, and then store the nitrite test kit properly. You may need to replace the reagents if they are running low.
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Nitrite test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using a nitrite test kit:
  • Always wear clean gloves when using the test kit.
  • Always store used waste reagents in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow reagents.
  • Do not smell the reagents.
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Image of hardness test kit.
Image of hardness test kit.






The hardness test kit is used to test the hardness of water. It usually comes with two reagents and a container.
Follow these steps to use the hardness test kit:
  1. Fill the container with the water sample.
  2. Add Reagent 1 to the water sample and mix it. This turns the water sample red.
  3. Add Reagent 2 drop-by-drop until the water sample changes from red to blue.
  4. The number of drops of Reagent 2 used is recorded and multiplied by a set number (this number will depend on the volume of water used).
  5. The result is the hardness of the water sample.




After use, rinse out the container. Wipe the container and the test kit dry, and then store the hardness test kit properly. You may need to replace the two reagents if they are running low.




Hardness test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using a hardness test kit:
  • Always wear clean gloves when using the test kit.
  • Always store used waste reagents in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow reagents.
  • Do not smell the reagents.


Alkalinity

Image of alkalinity test kit.
Image of alkalinity test kit.



The alkalinity test kit is used to test the alkalinity of a water sample. It usually comes with two reagents and a container.
Follow these steps to use the alkalinity test kit:
  1. Fill the container with the water sample.
  2. Add Reagent 1 to the water sample and mix it. This turns the water sample blue.
  3. Add Reagent 2 drop-by-drop until the water sample changes from blue to yellow.
  4. The number of drops of Reagent 2 used is recorded and multiplied by a set number (this number will depend on the volume of water used).
  5. The result is the alkalinity of the water sample.





After use, rinse out the container. Wipe the container and the test kit dry, and then store the alkalinity test kit properly. You may need to replace the two reagents if they are running low.




Alkalinity test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using this test kit:
  • Always wear clean gloves when using the test kit.
  • Always store used waste reagents in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow reagents.
  • Do not smell the reagents.




Image of nitrate test kit.
Image of nitrate test kit.






The alkalinity test kit is used to test the level of nitrate in a water sample. It usually comes with two reagents and a container.
Follow these steps to use the nitrate test kit:
  1. Fill the container with the water sample.
  2. Add the first reagent to the water sample.
  3. Add the second reagent and wait for the sample to change colour.
  4. Compare the colour of the water sample to the colour chart that comes with the test kit.
  5. Find the colour on the chart that matches the colour of the water sample, and take a reading of the value on the chart. This is the level of nitrate in the water sample.





After use, rinse out the container. Wipe the container and the test kit dry, and then store the nitrate test kit properly. You may need to replace the two reagents if they are running low.




Nitrate test kits can contain chemicals that can be harmful to you, to stock, or to the environment. Adopt the following guidelines when using this test kit:
  • Always wear clean gloves when using the test kit.
  • Always store used waste reagents in a suitable container for disposal later.
  • Avoid contact with skin and eyes.
  • Do not swallow reagents.
  • Do not smell the reagents.


Secchi Disk

Image of secchi disk.
Image of secchi disk.

The secchi disk is basically a painted disk attached to a length of cord, or a rod. It is used to measure the turbidity of water. The cord or rod is often graduated so that the depth the disk has sunk to can be measured.
To use a secchi disk:
  1. hold the cord or rod and slowly lower the disk into the water
  2. keep lowering the disk until it is just no longer visible
  3. note the depth of the disk by checking where the water level is on the cord or rod
  4. record this depth.




HYDROMETER

Image of a hydrometer
Image of a hydrometer




A hydrometer can be used to measure the salinity of a water sample. It is actually used to measure the specific density of a water sample, but you can calculate the salinity of a sample using a salinity/specific gravity conversion chart.
Follow these steps when using a hydrometer:
  1. Float the hydrometer in the fluid you want to test.
  2. Let the hydrometer sink. It will sink to the depth that is related to the water's density.
  3. Read the level from the graduated section of the tube.
  4. Record the result of your reading.
  5. Use the salinity/specific gravity conversion chart to convert the density of the fluid to a number that describes the salinity level of the sample.





A hydrometer has already been calibrated at the laboratory before it is sold. Always keep a hydrometer clean and dry when not in use. Store the hydrometer in a safe place where it cannot be damaged.