Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
24. EFFECT OF CHLORINE ON ALGAL GROWTH. Bobby Fujimoto. Department of Biological Sciences,
Saddleback College, Mission Viejo, California 92692
Algae growth is one of the principle problems of swimming pool care. Sodium hypochlorite
(NaOCl) is generally used to keep free chlorine levels at three parts per million (3ppm) to lyse algae cells.
The aim of this experiment is to discover if chlorine is significantly more effective than chloramine at killing
algae. Six experimental tubs were filled with 500mL of chlorinated water. One additional control tub of
500mL of the original creek water was also used in the experiment. The creek water came from where
the algae was sitting in before it was collected. The rest of the water came from a pool and was
measured with a pH of 7.6 and 3ppm free chlorine. The first three tubs were left with 500 mL of the
aforementioned water. In addition to the 500mL of aforementioned water 10mL of ammonia was added
to the last three tubs and they were labeled accordingly. Then, 50g of algae was added to each of the
tubs. No algae died in the control tub. The mean weight of dead algae in the pure free chlorine tubs was
26.960 +3.201g where N=3. The mean weight of dead algae in the free chlorine and ammonia tubs was
4.983 + 3.432g where N=3. A two sample t-test run between the two experimental groups showed
significance. The null hypothesis that pure free chlorine is as effective as or less effective than
chloramines was rejected where p