When the mercury rises during the summer months, your aquarium could be at serious risk of overheating. Unlike in nature, your fish can’t move to cooler waters—so it’s up to you to ensure their environment remains safe and stable.
High temperatures can stress all aquatic life, reduce oxygen levels, disrupt biological filtration, and even lead to fatalities. But with the right tools and techniques, you can easily maintain optimal water temperature—even during the hottest days of the year.
In this guide, we’ll explore 7 proven ways to keep your aquarium cool in hot weather.
1. Use an Aquarium Cooling Fan
A quick and cost-effective way to lower your tank temperature is by using an aquarium cooling fan. These fans work by increasing surface evaporation, which in turn draws heat away from the water.
Benefits:
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Inexpensive
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Easy to install
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Effective for drops of 1–3°C
Recommended Products:
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JBL ProTemp Cooler x300
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Tunze Aquawind Eco Chic
Tip: Point the fan diagonally across the surface for optimal evaporation.
2. Install an Aquarium Chiller
If you’re dealing with consistently high room temperatures or keeping sensitive species (like Discus or corals), a chiller is your best option. These devices operate similarly to a refrigerator, circulating water through a cooling system to maintain a set temperature.
Benefits:
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Precise temperature control
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Reliable for long-term use
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Ideal for marine, reef, and high-value tanks
Recommended Products:
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Teco TK 500 Chiller – Compact yet powerful; ideal for tanks up to 500L
Tip: Always pair your chiller with a temperature controller for automation and peace of mind.
3. Reduce your Lighting
Aquarium lighting, particularly fluorescent or high powered LED systems, can generate substantial heat. During summer, reduce your lighting period or switch to low-heat LED options.
Benefits:
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Less heat introduced to water
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Cost savings on electricity which can be redirected to cooling equipment
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Improved algae control
Tip: Use a timer or smart controller to automate your lighting schedule if you don't already.
4. Increase Airflow by Opening the Lid/Water Surface Movement
Opening or partially sliding your tank lid and covers allows for better heat dissipation through evaporation.
Benefits:
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Boosts surface cooling
- increase surface gas exchange
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No equipment needed and costs nothing!
Precautions:
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Use a fine mesh screen for jump-prone fish.
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Watch for increased evaporation and how that might affect your top up.
Tip: Careful when opening lids in homes with curious pets or young children.
5. Use Frozen Water Bottles for Emergency Cooling
This is a handy DIY solution for sudden spikes in temperature. Simply freeze a few water bottles (sealed) and float them in your aquarium or sump for short-term cooling.
Benefits:
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Cheap and quick
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Great for emergencies
Use With Care:
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Avoid direct contact with fish or delicate corals
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Don’t add ice directly—it changes salinity and can shock your fish and corals.
Tip: Always have 2–3 frozen bottles ready during heatwaves, they melt quickly!
6. Install a Temperature Controller
A temperature controller automates your tank's heating and cooling by switching devices on and off based on the current temperature. It seems obvious, but without a view on what is going on, your heater COULD still be running, een in a heatwave.
Benefits:
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One set up convenience
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Prevents overheating or overcooling
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Works with chillers, heaters, and fans
Tip: Place the temperature probe in the main display tank for the most accurate reading in warm weather.
7. Monitor Temperature Daily
Prevention is better than cure. During the summer, check your aquarium temperature twice a day—especially during heatwaves. Use a reliable digital thermometer for accurate readings.
Top Tools:
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Seneye Reef Monitoring System
- Neptune System Apex
Tip: Track your tank’s temperature over time using a journal or app—this helps spot long-term trends and prepare for future summers.
