Troubleshooting

There are many problems that may occur during this experiment. Here are some of these problems and some possible solutions:

Safety Issues

1. When experimenting with chemicals, it is extremely important to be careful and take many safety precautions. Here are some ways to prepare for any emergency:
    - Always wear safety goggles and gloves.
    - Always bring an extra set of clothing to the lab in case
     of a chemical spill.
    - Know where showers are in case of an emergency
     involving a chemical spill
    - Be extremely careful with chemicals, especially if they are poisonous, and always recap them between uses.

2. In case of emergency:
    - Alert an adult immediately in case of any chemical spill, especially if the
    chemical has spilled on a person.
    - Go to the shower/eye bath immediately if the chemical spill was large or in someone's
     eyes.
    - If a chemical has spilled on a smaller area of skin, flush the skin with water for at least
     1 1/2 minutes.
    - If chemicals have spilled on clothes, change into another set of clothing.
    - If chemicals have spilled on a table, floor, or other surface, clean the surface up
     immediately.

Contamination Tips
1. It is very important to keep all samples free from contamination. Here are some
    important ways to prevent this:
    a. General
        - Wash out any test tubes, funnels, soil measures, etc. after every use
        - Always wash out a soil extractor before taking another soil sample
        - Use sterile water
        - Always clean up the table using alcohol (70% isopropyl alcohol)
    b. Serial Dilutions
        - Use distilled (sterile) water for serial dilutions tests.
                                 - Use different test tubes for different dilutions; NEVER reuse the test tubes
                                  for another dilution.
                                 - Use different pipettes for different soil samples.
                                 - Use a micro-pipette with sterile tips to transfer the dilutions to the plates.
                                 - Recap the distilled water and the tips between uses.
                                 - Place the used tips in a sterile solution (10% bleach)

Troubleshooting for This Experiment
1. If there are limited amounts of yeast and mold plates, cut them in half vertically (so that they can stay closed).

2. If a soil extraction is not clear or a light yellow color, check to make sure that there is no mud inside the funnel. Allow the soil extraction to finish and re-filter the water, or redo the extraction.

3. If a magnesium test produces a large amount of precipitate which does not seem to follow the color chart, stir the sample with a stirring rod until the precipitate is mixed in well. Then follow the color chart and find the most similar color.

Suggested Suppliers:

The materials used in this experiment can be from any science kit brand. However, here are some suggested suppliers of materials which we found to be beneficial:
    - Soil kit/ Magnesium test: The LaMotte STH Series, Model STH-14. For more
     information, visit http://www.lamotte.com/component/option,com_pages/lang,en/mid,/page,49/task,item
    - Yeast and mold plates: 3M Petrifilm™ Yeast and Mold Count Plate. For more information, visit http://solutions.3m.com/wps/portal/3M/en_US/Microbiology/FoodSafety/product-information/product-catalog/?PC_7_RJH9U523003DC023S7P92O3O87_nid=VMHC06ZPSZbe29BDXSBJ7Fgl

Background by http://www.dragonartz.net/