heating rods in the aquarium
Typical heating element Source: Image on Wikimedia Commons License: CC Attr. SA 2.5 Author: Dr. David Midgley
When buying heating rods, products from well-known brands should always be preferred. Defects are reported more frequently in inexpensive products from unknown manufacturers.
Control heaters should be used on which the desired temperature is set and which automatically maintain this temperature. Overheating protection is useful. A relatively common defect is that the heater no longer switches off. An additional thermometer for regular monitoring of the temperature is therefore necessary. Due to measurement inaccuracies, the displayed temperatures of thermometers and heaters usually deviate from each other. These values are therefore only indicative.
Recommended manufacturers of heaters
The prices of the heaters differ significantly from different dealers, even for the same heaters.
Heating rods for small aquariums
For small aquariums, there are heating rods with 25 watts, but these are not available everywhere. There are also heaters with lower wattage, but these are often only offered by mail order.
As an alternative to heating rods, floor heating with a low wattage is also possible for small aquariums. The company Dennerle offers z. Consider, for example, a 9 watt heating cable. With a timer this z. B. can be set appropriately for small aquariums.
Are mechanical or electronic bar heaters better?
Electronic bar heaters have no moving parts. Contacts can therefore not wear out and there are no problems with aging bimetal. Theoretically, electronic rod heaters should therefore fail less often. At least the service life of the controller should be significantly longer than with mechanical heaters.
However, good, mechanical bar heaters last 10 years or more, so that an objective evaluation based on experience is hardly possible. There are cases in which 20-year-old heaters from Jäger still work, while the glass of new heating elements with electronic control cracks for no apparent reason. With old mechanical heaters, however, the temperature setting can often no longer be changed. Sometimes you can use a pipe wrench to change the temperature setting a bit.
Why heating rods crack
A relatively quiet cracking is usually caused by the expansion or contraction of the material of the heating rod when heating up or cooling down.
A relatively loud cracking occurs z. B. with the heaters from Tetra when they switch on or off.
moisture in the heater
Moisture can build up in a heating element over time. The heating rod does not necessarily have to be defective. According to one manufacturer, the moisture may be coming from the ceramic core of the heater. The heater is then still completely watertight.
In such cases, the heating rod should definitely be examined carefully. The finest hairline cracks in the glass are very difficult to detect. Leaking heaters must be replaced immediately.
If the stick is not damaged with certainty, it can be safely used despite the moisture inside.
Heat source outside the water
To prevent the fish, especially catfish, from burning themselves on the heater, external heaters are used from time to time. Since these are usually simply heating rods in their own container, there are no further advantages. An additional disadvantage is possible leaky connections. However, external heaters are usually significantly more expensive than normal heating rods.
Whether fish really burn themselves on a heating element has not been clearly proven. Frequently attributed injuries in fish may be due, at least in part, to bacterial infections.
If you touch a heating element under water, it can be quite warm, but the warm water is quickly carried away. It is actually unlikely that a healthy fish would remain lying on a heating rod until it burns itself.
For protection, there are perforated plastic shells on the market that can be placed on a rod heater. The shells consist of several parts, so they can be lengthened or shortened as desired, depending on the length of the heating element.
Tips on heating rods
Heating element and flipper (left) Enlargement Photo: Moritz Hertel
One cause of failure in heating elements is the contacts sticking together. Then the heater is on all the time. The water can be heated to such an extent that the fish die from the heat.
A simple method to avoid heat death is to use two low-power heaters instead of one large heater. A single, defective heating element cannot heat the water too much.
In the electronics trade, e.g. B. at Conrad Elektronik, there are electronic thermostats where no contact can stick. The heating rod is simply plugged into the electronic thermostat. Another advantage is that the temperature can be set more precisely. On the other hand, electronic devices can also fail.
How high a heating rod heats the water in the event of a fault can be easily determined by continuously heating the rod for a few days. Of course, this must not be tested in an aquarium with fish, plants and other creatures.
Heating rods with gold contacts are said to not stick. Contacts stick together due to the arc that occurs when the contact opens and closes. Due to the high temperatures, part of the material evaporates. This gives the spark its color. Another part becomes liquid. If the contact switches very slowly or vibrates, a spark will ignite again and again and the contact will stick or weld together over time. Gold does not protect against this effect.
A quick daily check of the aquarium to see if the temperature is right, the water level is right, the fish are healthy, etc. still provides the greatest security.
The functionality of the thermostat can be checked by occasionally changing the temperature setting of the heating element so that the heating element is switched on and off by the thermostat.
It is reported from time to time that a rod has become leaky. Of course, it cannot be ruled out that a rod will actually leak, e.g. B. by mechanical damage. Moisture often occurs in a heating rod, however, when condensation escapes from the ceramic core and collects in the rod. The condensation water is harmless and does not impair the function of the heating element. According to one manufacturer, this even shows that the rod is tight because otherwise the moisture would evaporate.
Jäger heating elements are known for their good quality. With older heating elements of this type, the temperature may no longer be adjustable after years of use. A possible cause could be the calcification of the rotary knob. There are also reports that the contacts in older staffs were no longer closing. In both cases, the water does not overheat.
Good experiences are also reported about the Tronic heating rods from Hagen. The condensation water effect described seems to occur more frequently with these bars.
What wattage should a heating element have
The wattage a heating element should have depends on the circumstances. Open aquariums require z. B. more heat output than covered aquariums. Common recommendations are 0.5 watts per liter of water for heated living spaces and 1 watt per liter for unheated spaces.
A slightly higher heat output offers more scope, e.g. B. to treat diseases, the temperature should be increased. On the other hand, a lower power offers more safety if the heater sticks and no longer switches off. The water doesn’t get quite as warm then.
It is safer to use a heating element with the lowest possible output and, if necessary, to use a second heating element.
The heating output is often oversized with the simple general recommendations. Therefore, the graphic indicates what heating power is required to increase the temperature by a certain value.