AQUARIUM APPLIANCES 



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open to allow the aquarium water to flow slowly through it and prevent 

 suffocation. In this way the large amount of dirt usually stirred up in 

 an aquarium at spawning time, and which can do the adhesive eggs no 

 good, is entirely avoided. The size of the net will depend somewhat 

 on the proportions of the aquarium, but the capacity of net (portion in 

 water) should be about twelve to eighteen inches long, ten inches wide, 

 and ten inches deep. In constructing, allow extra material for space 

 between top frame and surface of water. 



Fig. 106. Water Circulation by Air Pressure 



Constant Aquarium Filter. This device is for use in connection 

 with electric or water-power air pump. It is capable of a number of 

 variations, once the principle is understood. There are two columns of 

 water in the tubes, one solid and one punctuated by air bubbles, thereby 

 making it the lighter. This causes it to rise and therefore establish 

 circulation as long as air is supplied. A ^-inch diameter glass surgical 

 drain is shown at A. This should contain about eight small openings 

 and be suspended two inches above the sand. This is connected by a 

 short piece of rubber tubing to the rest of the system, which is of glass 

 tubing from 5-16- to ^-inch inside diameter. The dark sections represent 

 rubber joints, making the system more flexible, less liable to breakage. 



