Bloomin' Algae! (page 2)

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Author: Sarah Benton

Experimental Procedure:

  1. Label the jars 1-7 with the masking tape.
  2. Fill each jar with a mixture of ½ pond water and ½ spring water. Use the measuring cups to be sure you put the same amount of water in each jar.
  3. Jar 1 will be your control. Do not add fertilizer or detergent to this jar.
  4. Following the safety precautions on the fertilizer and detergent packaging wear gloves and wash hands as necessary as you follow the next steps.
  5. Jars 2, 3, and 4 will be fertilizer jars.
  6. Add ¼ tsp fertilizer to jar 2.
  7. Add ½ tsp fertilizer to jar 3.
  8. Add 1 tsp fertilizer to jar 4.
  9. Jars 5, 6 and 7 will be detergent jars.
  10. Add ¼ tsp detergent to jar 5.
  11. Add ½ tsp detergent to jar 6.
  12. Add 1 tsp detergent to jar 7.
  13. Cut 7 squares from the cheesecloth, large enough to cover the openings of the jars.
  14. Cover each of the jars with a square of cheesecloth and secure with a rubber band.
  15. Keep track of what is in each jar by making a chart in your notebook. See the example below. (Table 1)
  16. Set the jars in a sunny location.
  17. Observe the jars for 14 days. You may want to take photographs of the jars each day to show the changes. Make a written observation of what you see in the jars each day. Keep your data organized in a chart. See example below. (Table 2)
  18. On day 7 test the dissolved oxygen in each of the jars. Follow the directions that came with the dissolved oxygen kit. Note the dissolved oxygen measured in parts per million in your notebook.
  19. Continue to make daily observations.
  20. On day 14 test the dissolved oxygen in each jar again. Note the dissolved oxygen measured in parts per million in your notebook.
  21. Use your observations and dissolved oxygen data to draw some conclusions about what is happening in the water.
  22. You may want to use a line graph to show your results. See example below. (Figure 1)
Table 1
Jar 1
Jar 2
1/4 tsp fertilizer
Jar 3
1/2 tsp fertilizer
Jar 4
1 tsp fertilizer
Jar 5
1/4 tsp detergent
Jar 6
1/2 tsp detergent
Jar 7
1 tsp detergent
Table 2
Percentage of jar filled with visible algae
Figure 1


Terms/Concepts:  Eutrophication; Algal bloom; Dissolved Oxygen; Phosphates; Nitrates; Fertilizer; Decomposition; Rain runoff; Point source pollution; Non-point source pollution; Experimental control; Variables; Line graph


Project adapted from: “Eutrophication Lab” D. Gioffre, Hillsborough Middle School, Hillsborough, NJ 08844Funded by the National Science Foundation, Biocomplexity in the Environment Program, Award #0120453

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