16 AQUARIUM MANAGEMENT 



ment swim with such agility that it is difficult to see them under a 

 microscope. After they have satisfied themselves with a good swim they 

 attach somewhere and develop into a staid and sober mossy thread of 

 algae. Others become fully developed bits of delightfully green plant 

 life, of somewhat geometric shapes, idly suspended in the water, but 

 annoying the aquarist by turning it green. 



The conditions which favor the green water algae are too much light 

 and too many fishes. Fewer or smaller fishes and a reduction of light, 

 perhaps by the intervention of tissue paper, will usually clear the water 

 within a few weeks. Slightly acid water is more likely to stay clear. 



Suspended algae seems to occur in cycles and is only stimulated to 

 new growth by a partial change of water in the aquarium. On the other 

 hand if it is allowed to disappear naturally, the aquarium is likely to 

 remain clear for a long time. 



If one does not wish to wait for Nature to do the work, the clearing 

 can be hurried by adding one grain (by weight) of permanganate of potash 

 to each gallon of water. Remove snails or any tropical fishes, but the 

 goldfishes may safely be left in this solution. The water becomes at once 

 lavender, later brown and finally clears in a few days. It will not stay 

 clear, however, unless the conditions are changed. 



As a matter of fact, green water is apt to be healthy water. Many 

 a sick fish has been cured by being placed in it. 



If water has been very green and practically opaque for a long time, 

 one should be on the lookout for a turn to a yellowish brown color. This 

 change may occur over night, especially in warm weather. It means that 

 the suspended algae is dying. As its decomposition will soon kill the 

 fishes, an immediate change of water is advisable. 



Also very green water in strong light may develop gas which gets 

 inside the fins of fancy goldfishes, presenting an appearance of bubbles. 

 These are injurious but will disappear if the fish is placed in old, clear 

 water. 



Live Daphnia in plentiful numbers (Page 73) will clear green water 

 in a few days. 



To see the bottom of a tank or pool where the water is opaque, 

 take a bottle which is longer than the water is deep, press the base of 

 the bottle close to the point to be examined and look through the open 

 end. A milk bottle serves well in shallow water. 



Chemical Changes in Water. Many chemical changes are always 

 taking place in the aquarium. These are mainly due to the breathing 

 and the excrement of the fishes, as well as the action of plants. In time 

 an unbalanced condition is liable to develop, especially if there are not 

 plenty of healthy, growing plants. It is desirable to check up occasion- 

 ally on the water. Owing to the recent development of very cheap and 

 simple testing sets, this is an easy matter to do with sufficient accuracy 

 for our purposes. In the average aquarium the water should be main- 

 tained near the neutral point— neither strongly acid nor alkaline. If 

 it leans toward the acid side there will be less likelihood of disease and 

 cloudy water. The acid reading of the scale accompanying the test set 



