Video credit: Carolyn Madalo Chinguo (Malawi)
Description: Abdel Rahman El Gamal (Founder of the video channel)
This video was filmed in the WorldFish Center-Egypt during a regional training course.
This 9-min video demonstrates the field testing of total ammonia in water using the color disk kits. The video starts with water sampling emphasizing how to obtain a sample without air bubbles from a designated depth which was 30-cm in this video.
The demonstrated method can produce fast and reasonably accurate results especially when the individual color perception is high (individual sensitivity), especially this method depends on color comparison.
The analysis proceeds as follows:
Place the ammonia color disk on the center pin of the color comparator with the lettering facing out
Rinse the 2 viewing test tubes using the sample water before testing
Insert the blank test tube (only sampled water) into the left opening of the color comparator
Insert the ammonia-nitrogen test tube into the right opening of the color comparator. Add three drops of Nessler Reagent to the water sample and swirl to mix. A yellow color will develop if ammonia-nitrogen is present. Allow samples to sit for a maximum of 10 minutes.
Hold the color comparator up to sunlight or a lamp and view the openings in front. Rotate the color disk until a color match is reached then read and record the value of ammonium-nitrogen in mg/l as seen through the scale window.
The temperature and pH of sampled water should be measured in the same time of ammonia sampling. In order to obtain the toxic (unionized) component of total ammonia (NH3), consult a specialized table that considers the pH and temperature values. As a rule of thumb, the NH3 increases (and so the toxicity) as the pH rises.