TEOPICAL AQUARIUM FISHES 



105 



If one is not blessed with a heated greenhouse or a room of warm, 

 even temperature, artificial heating becomes necessary. There are several 

 devices which accomplish this purpose, but only a few are satisfactory. 

 In general those are to be avoided which concentrate the heat on a small 

 portion of the aquarium water. This action drives out oxygen and other 

 life-giving qualities and also produces uneven temperature for the fish to 



^^h 



Fig. 74. Indirect External Heater 



Fig. 73. Direct External Heater 



Fig. 75. Indirect System Through Base, Showing iMrRovEo Vapor Expansion 

 Hook Under Water 



pass through. Such an arrangement is shown in Fig. 7d. Aquarium 

 water is directly heated in the small outside reservoir and circulated 

 back again. With this device the water intake may easily become clogged, 

 which soon causes the water to boil. This heating method is frequently 

 used, but it is bad in theory and in practise. A better arrangement is 

 shown in Fig. 74, which is a complete hot water system not using the 

 aquarium water. The tubing is of copper, ^ inch inside diameter, and of 

 thin walls. Before bending any such work to shape it should be packed 

 quite hard with dry sand and the ends corked up. This prevents 

 buckling at the sharp curves. At the very top of the loop rising from the 

 heating coil should be bored a 54-inch hole and a small funnel soldered 

 around this. All hot water systems create some vapor. If this were 

 allowed to collect in the pipe there could be no circulation and boiling 

 would soon take place. The two open ends need not be soldered together. 

 They can be satisfactorily joined by rubber tubing, but this should be 

 arranged to occur in the rising side of pipe in the water. This whole 

 arrangement can be hooked over the edge of any aquarium and has the 



