A large container (approximately 3
gallons for a class that will have 6 groups) of water that has
"aged" should be available as a water source for set-up of all
microcosms. The aged water should be either aerated or left exposed
to the air for at least 24 hours to allow O2 and CO2 to equilibrate
with the atmosphere. This water also will serve as a control for
initial dissolved oxygen,
carbon dioxide, and
It is helpful to set up the microcosms
as simultaneously as possible. Testing the "aged water" for initial
chemical conditions can be done subsequently to microcosm setup.
Follow the instructions that come in the chemical kits to determine
initial dissolved oxygen, carbon dioxide, and pH levels.
Microcosm A - Aged water (untreated)
- Fill a jar to overflowing then seal the jar.
Microcosm B - Buffered
-Fill jar to overflowing and dissolve 100 mg of baking soda in it. Seal
Microcosm C - Minnows only
-Fill jar to overflowing, put in four minnow in it. Seal the jar.
Microcosm D - Minnows in buffered
-Fill jar to overflowing, put in four minnow, and dissolve 100 mg of
baking soda in it. Seal the jar.
Microcosm E - Elodea sp.only
- Fill a jar to overflowing and place 6 x3 inch sprigs of elodea
sp.in it. Seal the jar.
Microcosm F - Elodea sp.in buffered
-Fill jar to overflowing and dissolve 100 mg of baking soda in it. Place
6 x3 inch sprigs of Elodea sp.in it. Seal the jar.
should, ideally, be placed in a sunny window or under grow lights to
by Elodea sp.and serve as an additional control for conditions
in all microcosms. Allow approximately 20-30 minutes for conditions
to change in the microcosms. It is unlikely that minnows will become
distressed during this time.
Oxygen levels will change if excessive turbulence is created.
Follow the instructions included with the LaMotte or Hach kit
for determining the dissolved oxygen level in your sample. Record
Oxygen samples should be collected first from each microcosm.
Collect approximately enough water from each microcosm for your
DO test, being careful to avoid creating turbulence and splashing.
Remove minnows and plants from the microcosms
following collection of oxygen samples to avoid further change water
Carbon Dioxide Sampling - Collect
samples and test following instructions in your kit. Record data.
pH Sampling - Collect samples and test
following instructions in your kit. Record data.