Texas Watch Procedures

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  1. Check out a kit by signing your name and kit number.
  2. Check the kit for the following:

O pH tube        O 2 pH comparitors (black)    O wide range indicator

O titrator         O sulfuric acid (red cap)         O Alk. Pot. I. Azide

O Manganese sulfate         O Thiosulfate       O titration flask

O thermometer                  O Secchi disk        O Cond. Tester works

O plastic beaker                 O TX watch form  O disposal container

O conductivity/TDS standard or standardize at school first.


  1. Arrive at site and set thermometer out for air temperature.


  1. One student start titration. (#10 other side)


  1. Fill pH tube with river-water twice and rinse…fill to the black line

the 3rd time.   Add 10 drops of wide-range indicator.   Invert 10 times.  Compare to the colors in the black comparators and read pH to the 1/10 s.  Record the pH value.


  1. Read thermometer for air temperature and record the value.


  1. Place the thermometer and conductivity tester into the plastic beaker.  Fill to 1 inch depth with 710 ppm standard and rinse.  Repeat the rinse, and the 3rd time, fill to 1-2 inches depth with the 710 standard.  Turn on the meter and check to see the initial meter reading…record it.  Adjust the meter to read 710 PPM. (some meters have 2 white buttons under the battery cap…others have a small screw that you turn to adjust.) Record your adjusted to value as 710 ppm if you are successful.  Now read and record the standard temperature. 


  1. Dump out the standard and rinse 2 times with water and then fill to 1-2 inches with river water.   Read the TDS in parts per million and record it.  Record the water temperature and dump the water into your waste container.


  1. Lower Secchi disk at the standard spot for your test-site.   Lower the disk until it disappears and record that depth.  Now bring it back up and record the depth at which you can see it appear.  The values should be very close or the same.


  1. Titration:


a)Remove the lids from the twin sample bottles.

b)Hold both bottles in the same hand and rinse the bottles twice.

c)Fill both bottles with the same hand w/o getting bubbles…make sure the bottles are over the top full.

d)Cap the bottles.

e)Remove the caps of both bottles.

f)Add 8 drops of alkali potassium iodide azide and 8 drops of manganese sulfate.

g)Cap and invert 10 times.  Let settle to shoulders.

h)Uncap and add 8 drops of sulfuric acid. (red cap)

i)Invert 10 times.

j)Let settle until no particles can be seen.

k)Uncap titration tubes. (Larger clear cylinders w/ caps)

l)Rinse with fluid from step j twice, then fill to the line.

m)Fill titrator (hypodermic) to the 0 mark with thiosulfate.

n)Make sure to remove any bubbles.

o)Place titrator in cap hole and replace cap.

p)Add 3 drops from titrator, then uncap and add 8 drops of of starch indicator. (white cap)

q)Recap with titrator still in hole.

r)Add one drop and swirl to check color.

s)Repeat step r until one drop makes the solution turn clear.

t)Read titrator value in ppm of oxygen.

u)Repeat titration until you have 2 values within .6 of each other.  Record those 2 values and their average on your data page.


11. View river/lake site and record all other information on the data sheet.

12. Turn off conductivity tester and pack up kit.  Take waste disposal and pour it into a sink somewhere.