74 TROPICAL AQUARIA 



pass through. Such an arrangement is shown in Fig 54. 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 practice. A better arrangement is 

 shown in Figs. 55 and 57, which is a complete hot water system not 

 using the aquarium water. The tubing is of copper, J^-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 34"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. In Fig. 55 the arrangement can be hooked over 

 the edge of any aquarium and has the advantage that the aquarium 

 does not have to be elevated to heat from underneath. The first 

 filling of the system is not always easy. Water is poured in the 

 funnel until it will take no more. Then the hand is placed over the 

 funnel and the pipe turned upside down. Turn upright again 

 and put in more water. Hold at different angles. When it will take no 

 more water, try heat under the coil. If the water in funnel moves up and 

 down there is still air in the tube. Sometimes it can be removed by 

 actively filling and discharging a fountain pen filler in the opening. When 

 the water remains still in funnel when heated, it is all right to use. The 

 funnel must always contain water, or boiling will soon occur. If a filled 

 bottle with small neck is inverted, stood in funnel and secured in some 

 manner, it will last a long time without refilling. The copper tubing 

 should be heavily nickeled after bending into shape, as copper is fatal in 

 the aquarium. 



Fig. 56 shows a modification of the same idea with the pipe carried 

 through aquarium base. The little hollow hook at top of the hot water 

 system was devised by the writer to avoid the necessity of filling the 

 funnel, and to have the heater more concealed. The tubes within the 

 water are of glass, connected by rubber, the end hook also being a separate 

 piece. By removing hook the system is easily filled. When it is on, the 

 vapor collects in top of curve, and when enough has collected to force a 

 bubble out, a drop of water is automatically sucked back to take its place. 

 The air space in hook also prevents any circulation between hot water 



