Wetlands
   Frederick County Public Schools - Frederick, MD - Contact: Eddie Main - 240-236-4787 - eddie.main@fcps.org

 
 
 
  
 
How Much Oxygen is in the Water?
Dissolved oxygen (DO) is necessary for aquatic life in order to survive. Dissolved oxygen is measured in PPM or parts per million. Parts per million is the number of "parts" by weight of a substance per million parts of water. Fast moving water tends to have large amounts of oxygen, while slower moving water, especially stagnant water, has lower levels. Colder water tends to have more dissolved oxygen than warmer water. Most dissolved oxygen is introduced into water through aeration, flowing over rocks, or as a waste product of photosynthesis. It is generally considered that DO levels of at least 4-5 PPM are sufficient for most aquatic life, however, good fishing waters average about 9.0 PPM.
 
METHOD 1: Using Dissolved Oxgen Tablets
 
rinse bottle
 

Fill Bottle

   add 2 tablets  

shake bottle until tablets are dissolved
1. Rinse bottle thoroughly.   2. Fill bottle to overflowing.   3. Add two (2) tablets.   4. Invert bottle until tablets are dissolved.
             
Continue to shake bottle for 5 minutes   use comparator to determine oxygen level        

5. Wait five (5) minutes after dissolving.

  

6. Read oxygen content on comparator

  

 

  

 
 
METHOD 2: Using a Dissolved Oxgen Meter
 

oxygen meter

  

oxygen meter data

1. Once the meter is calibrated, hold the probe in moving water.

  

2. Read the meter in parts per million, PPM.
 
What Do the Results Mean?
The amount of oxygen available to aquatic organisms is controlled to a large extent by the amount of agitation or aeration of the surrounding water. The churning and swirling of rapidly moving water pick up a large amount of oxygen as opposed to slowly moving still water.
oxygen chart