Water Monitoring Testing

Dissolved Oxygen (DO)

Dissolved Oxygen is important to the health of aquatic ecosystems. All aquatic animals need oxygen to survive. Natural waters with consistently high dissolved oxygen are most likely health and stable enviroments capable of supporting a wide variety of aquatic organisms. Testing water samples for DO will let you know if the water you are testing is healthy and can sustain life. Follow the steps below to test for dissolved oxygen.

What You'll Need:

• Small test tube from your test kit.
• Two Oxygen TesTabs® - foil pack from your test kit that says "DO".
• A watch for timing.
• Protective gloves.
• Color chart from your test kit for comparing against your sample.

Dissolved Oxygen Test Procedure:

1. Submerge the small test tube from your kit into the water sample. Then, carefully remove the sube from the water sample, keeping the tube full to the top.
2. Take two Dissolved Oxygen TesTabs from the foil packs that say "DO" and drop them into the tube. Water will overflow when the tables are added.
3. Screw the cap on the tube. More water will overflow as the cap is tighened. Make sure no bubbles are present in the sample.
4. Mix by turning the tube over and over until the tables have disintegrated. This will take about 4 minutes.
5. Wait 5 more minutes for the color to develop.
6. Compare the color of the sample to the Dissolved Oxygen color chart from your kit. Record the result as ppm Dissolved Oxygen.
7. The Dissolved Oxygen (DO) test results are measured in ppm (parts per million), which is also called milligrams per liter (mg/L). 1 ppm is one part per million. Record your results in your field data sheet as ppm Dissolved Oxygen.

Comparing sample to the Dissolved Oxygen color chart.

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