AQUARIUM APPLIANCES 



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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 sys- 

 tem more flexible, less liable to breakage, less expensive in case of 

 break and makes cleaning of each section easy. (The tubes require 

 an annual cleaning.) Air is injected under pressure at C, which 

 should be five inches above lowest point of pipes. This starts the 

 flow, which is discharged into D, a small filter suspended in the cor- 

 ner of the aquarium, and just above water level. It may be made 



Fig. 220. Water Circulation by Air Pressure 



of glass, aluminum, porcelain or earthenware, and should approxi- 

 mate in size five inches in diameter by two deep, the bottom having 

 a few perforations. The best filtering medium in this work is absorb- 

 ent cotton, which should be laid on a few pebbles, glass bars or bits 

 of charcoal for good drainage. The force of air and the distance 

 between C and the surface of water determines the speed at which 

 the water travels. The lower the point at which air is injected, the 

 greater the speed. To start the system, disconnect at B, suck with 

 the lips to start siphon, re-connect while water is running. After 

 water in rise tube has reached aquarium level, turn on air-cock at C. 

 This cock should always be closed when air is not wanted and pump 



