GOLDFISH VARIETIES AXD 



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. 



Constant Aquarium Filter. This device is for use in connection 

 with the air pump referred to on page 10. 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 cir- 

 culation 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 3/^ inch inside diameter. The dark sections represent rubber 

 joints, making the system more flexible, less liable to breakage, less ex- 

 pense 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 corner of 

 the aquarium, and just above water level. It may be made of glass, alumi- 

 num, porcelain or eathenware, and should approximate in size five inches 

 in diameter by two deep, the bottom having a few perforations. The best 

 filtering medium in this work is absorbent 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 deter- 

 mines 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 not work- 

 ing, in order to prevent water backing up into air pipe. All rubber joints 

 should be tightly secured by wrapping with thread or narrow strips of 

 electric tape. Rubber cement spread on connecting surfaces helps make a 

 good job. If there is danger of glass tubes being broken it is best to use 

 pipe of block tin. For salt water, use glass or lead. 



Instead of filtering at top of aquarium it is possible to pass the water 

 through a big, large-necked bottle of sand at the lowest point of dip. Both 

 tubes pass through a rubber cork, the dirty water being carried to bottom 

 of bottle, discharged in a layer of pebbles, brought upwards through fine 

 sand and taken ofif by rise pipe just inside of cork. The sand should not 

 quite fill bottle. Cork must be securely tied down. This is a nice arrange- 



