120 MARINE AQUARIA 



inmates. The surface of the water takes up enough oxygen to maintain 

 a few animals, but if our ideas are more ambitious it will be best to install 

 an air pump such as referred to on page 11. This will more than com- 

 pensate for any plant deficiency, especially if the air is liberated in very 

 small bubbles. In the case of large marine aquaria where the water is 

 constantly pumped out, filtered and returned, the oxygenating is accom- 

 plished by a very simple and, at the same time, clever device. The water 

 is discharged with some force from a small pipe into the open end of 

 another pipe just enough larger that the water discharge pipe will fit 

 loosely in it. The second pipe is the liberator, and is carried to the bottom 

 of the aquarium, where it is bent to a right-angle so as to shoot the air 

 somewhat horizontally across the aquarium. If the aquarium is very deep 

 (3 to 5 feet), the intake of liberator pipe should extend about 8 inches 

 above the surface of the aquarium. Otherwise the air in the column of 

 water in the liberator pipe would make it so light that it would back up 

 instead of discharging in the bottom of the aquarium. In shallower 

 aquaria the liberator pipe will not need to stand so high above water- 

 level. By this method the air bubbles are mostly very minute, producing 

 the eitect, from a little distance, of smoke. The high specific gravity of 

 marine water enables us to break up the air much finer than in freshwater. 

 Marine Aquaria. While it may not always be possible to entirely 

 avoid having metal come into contact with the water of the marine 

 aquarium, this risk should be reduced to a minimum. Copper, brass and 

 zinc are particularly dangerous. The metal now coming into use, Monel 

 metal, is not entirely free from copper, but, on the whole, is very satis- 

 factory, and has the advantage of great strength as well as a pleasing 

 light color. Marine bronze is also good and not so expensive as Monel. 

 Iron pipes and valves lined with lead are now made, especially for resisting 

 chemicals. These are very fine for carrying marine water to and from 

 the aquarium. For the aquarist working on a comparatively small scale, 

 lead pipe is best. 



With the all-glass aquarium we have no metal problem to contend 

 with. Aquaria of the smaller sizes are satisfactory for marine purposes 

 if not overstocked. In the executive officers of the Battery Park 

 Aquarium in New York City, they have in successful operation a number 

 of jar aquaria, one of them having continued without interruption, 

 except for change of animals, since 1900. This should give reassurance 

 to those who hesitate to establish marine aquaria. 



In using metal-framed aquaria a narrow strip of glass should be 

 placed over the cement in the corners. A recent improvement is a glass 

 rod of suitable diameter, say about one-quarter inch. This can be pressed 

 through the soft cement all the way to the glass and the surplus cement 



