Volunteer Water Monitoring

Transparency Tube

Submitted by Ron Ohrel, Center for Marine Conservation

Materials:

• Clear plastic cover from fluorescent light tube
• Two plastic caps from fluorescent light tube cover
• Small piece of white plastic
• Silicone cement
• Meter stick
  
  Building the Transparency Tube:
  1. Remove the caps from the tube.
  2. The caps should have oval-shaped holes near at the center of their closed ends. If the holes do not exist, cut a 1.5 cm x 2.5 cm hole in one of the caps.
  3. Place the white plastic piece inside one of the caps (if only one cap has a hole, place the white piece inside the cap without a hole).
  4. Cement the other cap snugly inside the first cap, so that the white plastic piece can be seen through the hole.
  5. Slide the tube into the caps so that the black and white pattern made by the plastic and caps can be seen when looking down the tube.
  6. Cement the tube to the caps.

  Notes:

  · Unless a valve is installed, the volunteer will have to incrementally pour water out of the tube until the black and white pattern can be distinguished.

  · Use the meter stick to measure the water height where the user can no longer see the white plastic. Instead of using the meter stick each time a sample is measured, the volunteer can mark the tube at appropriate intervals (e.g., centimeters) using a permanent marker.

  · The tube may be shortened to make it easier to carry. This can be accomplished by cutting the top off with scissors. However, the tube should not be shortened beyond the range of typical transparency readings (e.g., if tube readings are often found between 100-150 centimeters, make sure the tube is long enough to accommodate those readings).

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