74 MAINTAINING FISHES 



(2) Methyl orange indicator (0.05% aqueous solu- 

 tion). 



TITRATION procedure: The same sample 

 used to determine the phenolphthalein alkaHnity can 

 be used to determine the methyl orange alkaHnity if 

 the phenolphthalein end-point has been reached ac- 

 curately or if no pink appeared when the phenol- 

 phthalein indicator was added. Add several drops of 

 methyl orange indicator, then titrate with the .02N 

 sulfuric acid to the first definite change from yeUow to 

 salmon pink or pinkish orange color. The number of 

 miUihters of sulfuric acid solution used multipHed 

 by 10 and the correction factor is the p.p.m. of methyl 

 orange alkalinity expressed as p.p.m. of calcium car- 

 bonate. 



Ammonia 



Ammonia is perhaps the best index of the quan- 

 tity of accumulated metabohc waste in aquaria, and 

 studies involving an interest in metabolic waste would 

 likely require an analysis of ammonia. However, due 

 to the difficulty of making ammonia determination it 

 is felt best to omit the procedure here and refer the 

 interested reader to Standard Methods for the Exami- 

 nation of Water, Sewage, and Industrial Waste, 

 Tenth Edition, American PubHc Health Association, 

 et al,, 1955. 



