Chemical Variables of Aquarium Water 

 and Their Determination 



IN THE present work we will deal only with those 

 chemical variables which are most apt to aflFect the 

 maintenance of fishes in aquaria and which can be 

 readily measured. We have omitted variables such as 

 acidity, salt content, and various widely occurring 

 compounds such as the sulfates. For a consideration of 

 these variables the reader is referred to the following 

 works: Standard Methods for the Examination of 

 Water, Sewage, and Industrial Waste, Tenth Edition, 

 American Public Health Association, et al., 1955j and 

 Limnological Methods, Welch, 1948. 



Dissolved Oxygen Determination 



Oxygen is not very soluble in water, yet fishes 

 are dependent upon the small quantities that are pres- 

 ent. Dissolved oxygen in water is replenished by dif- 

 fusion from the atmosphere and photosynthesis of 



