Summer is finally here! And we're hoping the weather stays sunny and warm! However, it is important to consider that rising temperatures, especially during heat waves, can affect your tank's stability. Tropical marine life is used to very stable conditions in the wild, and temperature is no exception. Even small fluctuations in water temperature can cause stress to fish, corals, and invertebrates. When things heat up too much, oxygen levels drop, metabolism increases, and sensitive species can struggle to adapt.
Here are a few of our tips to consider:
Monitor your tank's temperature closely
It's key to consistently monitor the temperature of your tank using a digital thermometer. Consider setting temperature alerts if using a controller. This System Upgrade Kit for Red Sea aquariums includes a highly accurate temperature monitoring system, for example.
Here’s a quick guide:
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24–26°C (75–78°F) – Optimal range for most reef systems
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Below 23°C (73°F) – Too cold for many tropical marine species; may slow metabolism or stress corals
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Above 27°C (80°F) – Can cause stress in corals, reduce oxygen levels, and increase the risk of disease or bleaching
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Over 29°C (84°F) – Potentially dangerous; high risk of coral bleaching and oxygen depletion
Consider improving airflow and cooling your tank
Ensure you have good ventilation around the tank and sump, and if you have them, ensure cabinet doors are open below your tank to reduce heat buildup.
Use cooling tools if needed, like using frozen water bottles in the sump as a temporary quick fix, but you may want to consider getting a refrigerated chiller; this one from D-D DC300, for example, actively reduces water temperature to your desired setpoint, helping prevent overheating during the hot weather.
Adapt the lighting in your reef tank
Since high-intensity lighting contributes heat, you may want to reduce the intensity on hot days or just turn it down on during the cooler hours of the day (early morning or late evening). LED lighting systems produce less heat, so you may want to consider upgrading.
Reduce feeding and keep an eye on livestock
As temperatures rise, your tank’s biological load can become harder to manage. Extra food means more waste, which leads to elevated nutrient levels, something that can quickly throw your system off balance in the heat. During hot spells, it’s a good idea to slightly reduce feeding frequency or portion sizes, especially if your livestock seem less active.
At the same time, watch your fish, corals, and inverts closely. Signs like reduced polyp extension, rapid breathing, or unusual behaviour may indicate heat stress. Catching problems early makes all the difference in keeping your livestock healthy through the summer.
Keep water quality in check
Warm water holds less oxygen, and increased temperatures can cause everything in your tank, from fish to bacteria, to use more of it. That makes good water quality more important than ever. Regular testing for pH, oxygen levels, and nutrient balance helps you stay ahead of any issues. We have a range of test kits, including these Hannah test kits, that help you to monitor your tank.
To support oxygen levels, consider boosting surface agitation using wavemakers or adjusting return flow.
If you have any questions about your tank care as the weather warms up, please don't hesitate to contact our team. We're always happy to advise!