How to cool the aquarium water
© Romolo Tavani – stock.adobe.com – ID: 269437588
In warm weather, the aquarium water can heat up quickly. Most fish species can withstand higher temperatures for a period of time, even for several weeks, if the fish are otherwise healthy and fit.
Often, the heat does not bother the fish at all. However, warmer water can hold less oxygen. This can lead to a lack of oxygen in warmer water.
In such situations, the first step can be to add oxygen to the water with an oxygen stone or diffuser.
If the warm period lasts longer or species that are sensitive to heat are kept, the water can be cooled using various methods.
Ways to cool the aquarium water:
- Water changes with cold water as an immediate measure
- Open or remove the aquarium cover.
- In the case of covers with a light box, cool the light box.
- Lay ballasts outside of the light box.
- Cool the water surface.
- In aquariums with pendant lights, hang the lights higher.
- Use mobile air conditioning for the room.
- Place ice cubes or cold packs in the aquarium water.
- Use flow-through cooler for the aquarium.
Open or remove cover
It is often sufficient if the cover is opened slightly. The warm, moist air above the aquarium can then more easily escape into the room and be replaced by cooler, drier air. The water surface is thus cooled even without a fan. The cooling effect is significantly increased when a fan constantly brings fresh air over the surface.
To prevent fish from jumping out of the aquarium, the aquarium can be secured with a plastic net, plastic-coated rabbit wire, a perforated plexiglass pane, a mosquito net or similar.
It has a similar effect if you put a damp towel on an aquarium pane and cool the towel with a fan.
Cooling of the light box
Holes are cut into the light box at suitable points and fans are installed there to suck out the hot air. Ventilation slits are cut in another, suitable place, which then provide fresh air. In addition, the ballasts can be moved outside of the light box.
Cool water surface (DIY)
The air between the water surface and the cover is additionally heated by the lighting. The aquarium water can therefore become warmer than the air in the room. If the heated air is simply blown out, the water heating is reduced. The temperature level usually levels off by one to two degrees above room temperature. In addition, evaporation effects not only prevent heating, but also cool the water.
Holes are drilled in the flaps of the cover and fans are installed there. Depending on the cover, the fans can also be attached to the cut-outs for hoses etc. They can be attached with hot glue or with screws.
According to some reports, cooling performance is better when the fans blow air into the aquarium. There are usually enough cracks in each cover to allow for pressure equalization.
According to other reports, the cooling effect is better when the air is extracted from the aquarium.
Openings around the fans should be sealed airtight. Air takes the path of least resistance. If the fans are not sealed, air will bypass the outside of the fan and back out through the fan. The fans scoop a lot of air, but there is almost no air movement over the water.
A fine net should be stretched in front of the fans from inside the aquarium so that jumping fish or climbing invertebrates do not injure themselves.
The fans can also be secured with fan protection wire. A third guard wire can connect the fans. The fans connected in this way are attached to a large paper clip with wire. The clip is attached to the edge of the pool in such a way that the fans blow well onto the water surface.
It’s better to use larger fans, which can then spin slower than small fans, which will eventually make loud noises due to the high speed. An 80 mm fan in a PC must have the same cooling capacity, e.g. B. only run half as fast as a 60 mm fan.
Suitable are PC fans with 12 V be operated via a suitable power pack. In addition to the operating voltage, usually 12 volts, the fan also shows the power consumption of the fan. The power consumption of PC fans is very low, so smaller plug-in power supplies are also suitable. Controllable 12 V power supplies with which the speed can be regulated are good. If two fans are used, they are connected in parallel. So each fan has the full voltage. When connected in series, each fan has half the voltage.
If the fans have DC voltage, the power supply must also supply DC voltage. The safest thing is a stabilized, not too cheap plug-in power supply with exactly the output voltage that is required.
If the cover is not to be modified, a standard room cooling fan can be set up to blow the air over the water surface.
These processes are based on the fact that heat is dissipated through the evaporation of water. The water-saturated air above the aquarium is transported away. Accordingly, some water evaporates from the aquarium and has to be refilled. On the other hand, 30 g of evaporated water has the same cooling effect as 1 kg of melted ice. In addition, the lighting is cooled, which otherwise gives off heat to the water.
Water has a high heat of vaporization of 40.6 kJ/mol, i.e. about 2255 kJ/liter of water. In this case, heat corresponds to cold. In order to evaporate 1 liter of water, about 2255 kJ of energy is withdrawn from the environment. If 4.18 kJ of heat is extracted from a liter of water, it cools down by 1°C. This corresponds to the so-called heat capacity of water.
With 2255 kJ of heat extraction, i540 liters of water can be cooled by 1°C if this heat is only taken from the water.
If 10% of the heat for the evaporation of the water is actually extracted from the water and not e.g. B. the outside air, a 50 liter aquarium cools down by about 1 ° C when 1 liter of water evaporates. The calculation applies when the pool is 100% insulated and not reheated at the same time.
Generally speaking, a 50 liter pool cools down by 1° Celsius when 1 liter of water evaporates. Details also depend on the air temperature. However, these are all examples that cannot simply be extrapolated. When cooling 500 liters by 5°, 250 liters of water do not necessarily evaporate.
An existing fertilization with CO2 may have to be increased somewhat because the exchange of air between water and air is improved.
Cooling with ice cubes or cold packs
1 kg of ice consumes 80 kcal of heat when defrosting. 1 kg of water contains 1 kcal per degree of heat. With 1 kg of ice you can cool 80 l of water by one degree.
A bucket with 10 liters of water that is 10 degrees cold will cool 100 liters of water at 30 degrees to 28 degrees.
When water evaporates, 1200 kcal per liter are carried away.
Cooling the aquarium water with ice, cold packs, etc. requires a lot of energy and is not particularly effective. This solution can actually only be seen as an emergency solution for smaller aquariums up to approx. 150 liters.