To keep tropical fish in the conditions to which they are accustomed, it is necessary to maintain the temperature of the water at an average of 70° to 75°F. There are various ways of doing this according to the facilities at the disposal of the aquarist.
The easiest and most efficient is the electrical method. The heat is provided by an immersion heater, which is a coil of resistance wire wrapped around a ceramic former, much the same as a bar element of an electric fire. The former is in a heat-resistant glass tube, and sealed with a rubber stopper through which the connecting wires are passed. These heaters can be obtained in various wattages to suit different sizes of tanks.
Thermostats in Fish Tank Heaters
A thermostat controls the temperature by switching on the heater when it drops below a preset figure, and off when the temperature reaches the temperature you require. The thermostat is made of a bimetal strip which has different coefficients of expansion, causing the strip to bend away from the contact when heat is applied, and vice versa. The thermostat clips over the top edge of the aquarium, and the adjustment of temperature is controlled by a knob which alters the pressure on the strip.
Another type of thermostat has an adjusting screw inside the tube, and a rubber stopper, similar to the heater. This type can be laid on the bottom of the tank. This has the advantage of allowing you to lower the depth of water for breeding purposes. The disadvantage is that you have to remove it for adjustment.
The heater and thermostat are supplied complete. Do not worry if at first the thermostat varies as much as 10°F. Do not try to correct this with the adjusting screw, as this screw only controls the temperature at which the strip will break and make contact. A quarter turn on the contact screw is usually enough to decrease the pull of the magnet sufficiently to bring it within the required range. The ratio of electrical power to volume of water is 10 watts per gallon of water.
When the contacts of the thermostat make and break, they cause a tiny spark which can cause a disturbance, both to radio and television sets. This can be overcome if a 0T microfarad tubular capacitor is connected across the contacts.
To do this, bare the two wires leading from the thermostat as near to the top as possible, and then wrap the capacitor leads around the bared sections, one from each end of the capacitor to each wire, and solder securely.
Make sure the bared portions of wire are then covered completely with insulation tape to avoid a short circuit. A further precaution is to cover the whole capacitor by wrapping insulation tape around the complete assembly.
The type of capacitor used must be of a robust nature, it has to withstand the mains current, therefore it is advisable to tell your dealer the use to which it will be put so that he can give you the correct type.
Another type of heater combines both heating elements and thermostat. The glass tube is mounted vertically in the tank, so that the lower section of the tube containing the heater is well down in the water. This arrangement may be suitable for small tanks, but it probably concentrates the heat energy in too small an area, and too locally.
The flexible heater is another method of electrical heating which is becoming widely used. This consists of a flexible loop containing the element which can be arranged around the inside of the tank, just below the surface of the sand, and is virtually invisible except for the connecting wires.
The choice of equipment is obviously a matter of personal choice, but there is much to recommend two heaters, suitably positioned in the tank to give uniform distribution of heat, and an outside fitting thermostat. These clip on the frame in close proximity to the glass and are easily adjusted for temperature control.
Small aquariums may be heated with an electric light lamp only, with or without a thermostat. We have found from experience that it is not advisable to use this method in a tank over 1 ft. in length, but if you use this method to heat an aquarium which is only used for quarantine or some similar job, it saves the expense of other equipment. The lamp is used in a box, and the aquarium stood on top.
If your tank is 12 in. X 6 in. X 6 in., the outside dimensions of the box will be 12 in. X 6 in., and it will be about 3 in. deep. Line the inside with thin asbestos sheet, and make a few holes for ventilation. Screw a base fixing lamp holder inside— you can use the same screws to hold a strip of aluminum , bent over the bulb to avoid the direct heat of the lamp, which may tend to crack the glass. We have found a 15 watt lamp is sufficient, but in very cold weather a 40 watt lamp is necessary. When you have done this cover the top of the aquarium with a sheet of glass, and always have sand on the bottom, otherwise the unnatural position of the light will cause discomfort to the fish.
Post Title: Does My Fish Tank Need A Heater?