How to Cool Down Tanks

How to Cool Down Tanks

There’s no denying that the temperature in aquariums can rise to very high levels during the summer and your aquarium fish and shrimp will definitely struggle to cope with the situation.

Cooling techniques are paramount when this occurs. And you need to employ these techniques quick enough to lower your aquarium’s temperature, or your tank inhabitants will suffer with the travails that come with overheating.

In this article, I will be looking at several methods of cooling down fish tanks (like water changes, lighting control, using chillers, fans, ice packs, etc.) in the event of increased temperatures.

Why The Aquarium Temperature Increases

The temperature of an aquarium may rise considerably in the hot summer months when the overall temperature of the environment increases.

Higher temperatures are quite common during the summer and you should be ready to take adequate measures to prevent/control overheating in order to preserve the life of your aquarium inhabitants.

Other likely causes of elevated temperature are:

  • using an artificial lighting source that emits too much heat,
  • longer photoperiods/excessive lighting,
  • lack of air conditioning,
  • mounting the tank close to a window, and
  • faulty aquarium equipment.

Therefore, do monitor the aquarium water temperature using a suitable thermometer and jot down the readings each day on a journal. This will help you notice any sharp or drastic increase in the temperature of your aquarium water.

As a result, you would be able to take corrective measures to drive it lower to the normal, recommended temperature depending on the aquatic species in your tank.

Effects of Elevated Temperature in The Aquarium

Higher temperatures often lead to the depletion of oxygen levels in an aquarium. The reason for this occurrence is because cool water holds more oxygen content than warm water.

Warmer temperatures decrease the level of dissolved oxygen in the aquarium water, and on the contrary, cooler temperatures increase the dissolved oxygen levels.

Additionally, excessive temperature conditions often aid the growth and proliferation of algae in your aquarium. Elevated temperatures have been linked to lingering algae problems in aquaria.

Furthermore, higher temperatures cause a rise in the and fish, and this will result in more excreted waste, reduced life span, and faster deterioration of the aquarium.

Although most tropical fish species can tolerate water temperatures up to 80° F (27 °C), it revolts against optimal health and makes them prone to diseases. As for the dwarf shrimp, only Sulawesi shrimp species can thrive in it.

Hence, it would be wrong to allow a prolonged spell of increased temperature in your aquarium, knowing the severe harm it can cause to your aquarium animals.

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Effective Cooling Techniques

There are several methods of lowering higher temperatures in tanks. However, depending on the severity of the high temperature in your aquarium, you can employ the following methods to cool down the temperature.

1. Turning off the aquarium lights:

It is common knowledge that many aquarium lights do emit a lot of heat as they supply illumination to tanks.

Notably, artificial light sources like T5 and T8 bulbs, metal halides, VHO lamps, do give off a high amount of heat in comparison to a light-emitting diode (LED) fixture.

Nonetheless, turning off the artificial lighting will help reduce the aquarium’s temperature during hot periods.

While at it, make sure to boost the DO levels in your tank through aeration with air pumps/air stones and adequate surface agitation — since the live plants will transition from photosynthesis to respiration in the absence of lighting; thus, using up a lot of the dissolved oxygen.

In addition, you may turn on the lights during these days, but be sure to maintain shorter photoperiods to decrease heat generation.

Pros Cons
Simple Helps with a slight increase in heat
Cheap Lack of lighting may cause problems for some aquarium plants
  Slow effectiveness

 2. Open the aquarium hood:

This is a viable option if you do not have escape artists (like freshwater crabs and crayfish) or jumping fish in your aquarium. By this I mean aquatic species that are highly skilled in evading the confines of an enclosure.

Simply open the aquarium hood/lid and install an aquarium cooling fan to blow directly across the surface of the water.

The cooling fan helps in cooling down the water temperature and it also keeps the aquarium lights from overheating. Depending on the size of the aquarium, the cooling fan will cause a temperature drop of 1 – 3 °C (or 2 – 6 °F) in 24 hours.

Important: Keep in mind that this equipment performs the role of cooling at the expense of evaporation, i.e. reducing the volume of water in the aquarium. Due to this resulting effect, do well to top up the aquarium water to the usual level with dechlorinated or reverse osmosis water.

Pros Cons
Simple Helps with a slight increase in heat
Cheap Slow effectiveness
  Requires top-offs

3. Air conditioning:

Keeping the exterior environment cool is essential as it plays a major role in dictating the temperature condition of your aquarium.

Install blinds in your aquarium room to block out sunlight during the day. Also, run an air conditioner to lower ambient temperature in the room, and in turn, it will help cool down your aquarium’s water temperature.

Pros Cons
Moderate effectiveness Helps with a slight increase in heat.
Controllable Requires additional equipment
  Requires top-offs

4. Ice packs:

In as much as ice packs and frozen water bottles are affordable, easy, and quick solutions to elevated temperature problems — they are more suited for emergencies i.e. when the aquarium water temperature is exceedingly high.

Important: Do not put ice cubes directly into your tank unless you make them with reverse osmosis or dechlorinated water. You need to use a bag for that.

Anyway, do note that the addition of ice packs and frozen water bottles to an aquarium may cause a drastic drop in the temperature levels, thereby leading to a temperature shock, so use these cautiously.

Note: Fish, shrimp, crabs, crayfish, snails, etc. are all “cold-blooded” animals. In other words, their body temperature completely depends on the temperature in their surrounding environment.

  • Throw in some ice packs into the aquarium and check the temperature reading after 30 minutes.
  • If the temperature is dropping too fast (more than 1 °C or 2 °F), remove the ice packs and wait for an hour for everything to stabilize.
  • Then check the temperature from an opposite end for the most accurate reading. The decision to continue or quit would be determined by the result after the said period.

Rapid temperature drops will make your animals stressed or even sick. Ideally, you should aim for little drops — no more than 3 °C (6 °F) in 6-8 hours.

Important: Only float ice packs in a tank with ample flow. Having enough flow in the tank ensures that the cold diffuses easily so it doesn’t get to shock your aquarium fish.

Overall, this method presents a risky and somewhat daunting way of lowering the aquarium water temperature.

Pros Cons
Simple Uncontrollable (risky)
Fast effectiveness  

5. Water changes:

Just like the ice method, water changes are more suited for emergencies.

This technique involves the use of a medium —cooler than the present aquarium water. In this case, slightly cooler water provides a short-term fix to the raised temperature.

All you need to do is to replace about 25% of the aquarium water with cooler dechlorinated water, and it will markedly lower the temperature of your tank.

Don’t change too much of your aquarium water to avoid dropping the temperature by more than 1 – 3 °C (or 2 – 6 °F) within a short period because rapid swings in temperature is detrimental to the health of aquatic species.

Whenever the situation allows, it is better to do several small water changes instead of a big one.

In addition, shy away from using very cold water for partial water changes as it causes extreme stress to fish and makes them susceptible to diseases. In shrimp tanks, big water changes may cause molting problems.

Pros Cons
Simple Can cause stress to animals
Moderate effectiveness  

6. Aquarium chiller:

Chillers are quite costly, but their effectiveness in controlling temperature is unmatched.

This aquarium equipment does a great job at cooling down the temperature of tanks and keeping it at the right level no matter the season; of course at the expense of high purchase cost and high electric bills.

Well, if you have made up your mind to deal with the excess heat in your aquarium and to also keep the water temperature at safe and stable levels — go ahead and obtain an aquarium chiller rated for your tank size, anything lesser won’t guarantee the desired result. Trusted brands include (links to Amazon):

Aquarium chillers are capable of cooling down tanks at a much faster rate compared to other methods but do not abuse this advantage.

Moreover, you can set automatic on/off toggles, read current temperatures on its LED control panel, and make temperature adjustments with its temperature controller. Some chillers come with this piece while others don’t — so you may have to purchase a separate temperature controller to use these awesome features.

Pros Cons
Guaranteed success Expensive
Stable and controllable Complex

7. Aquarium fans:

By blowing a fan across the surface of the tank, we increase evaporation. As a result, we cool it down.

Aquarium fans are a cheaper solution compared to aquarium chillers which work as niche refrigerators. Of course, they cannot provide stable results and keep the temperature at certain levels but still … one day they can come in handy.

Check out the price on Amazon.

Pros Cons
Moderate effectiveness Helps with a slight increase in heat.
Controllable Requires additional equipment
  Requires top-offs

In Conclusion

Higher temperatures for a prolonged period of time can spell doom for your aquarium. That’s why you should utilize the listed measures to prevent the temperature of your fish tank from reaching extreme levels.

Don’t panic when you witness raised temperature in your aquarium, the worst thing to do at this point is dropping the temperature rapidly within a short time.

While cooling down your tank, be sure to lower the temperature gradually till it returns to the normal level. The safety of your aquarium fauna is a top priority, so do not misuse any of the aforementioned cooling methods.

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