The role of stable water temperature in promoting healthy coral growth

Table of Contents

Stable water parameters, including temperature, are crucial for the optimal development of corals in marine aquariums. Temperature fluctuations can stress corals, which affects their ability to grow, reproduce, and survive.

Importance of stable temperature

Coral skeleton growth: Corals build their skeletons using calcium dissolved in seawater. This process, known as biomineralization, is most efficient within a specific temperature range. Too low or too high temperatures can slow down or stop this process.

Health of symbiotic algae: Most corals contain symbiotic algae called zooxanthellae in their tissues, which are essential for their nutrition. These algae perform photosynthesis, providing nutrients to the corals and helping eliminate waste. A stable temperature supports optimal photosynthetic activity of these algae.

Optimal temperature range

For most reef corals, the ideal water temperature is around 25°C. Maintaining a temperature range of 25-27°C is recommended to preserve the health and vitality of the corals.

Long-Term Effects of Unstable Temperature

Temperature fluctuations can affect not only coral growth but also the entire reef ecology. These changes can lead to shifts in species composition, with thermophilic species being replaced by those more resilient to variable conditions, potentially having long-lasting consequences for biodiversity and reef structure.

Water temperature changes can seriously affect various aspects of coral life, especially those related to their physiology and ecology. Here are a few key processes that can be impacted:

Photosynthesis: The symbiotic algae in coral tissues, which provide most of the needed energy through photosynthesis, can be disrupted by temperature changes. If the temperature is too high, zooxanthellae may be expelled from the corals, leading to coral bleaching.

Growth and regeneration: Corals use calcium from the surrounding water to build their limestone skeletons. Temperature fluctuations can disrupt corals’ ability to absorb and use calcium, affecting their growth and ability to regenerate after damage.

Reproduction: Thermal stress can impact the reproductive cycles of corals, disrupting the release of gametes or the synchronization crucial in mass spawning processes, which affects coral population renewal.

Disease resistance: Stress related to temperature changes can lower corals’ overall resistance, making them more susceptible to diseases. Elevated temperatures are particularly favorable for the development of certain pathogens.


For marine aquarium hobbyists, it is vital to use a proper cooling and heating automation system that maintains stable water temperature. Regularly monitoring the temperature and using automatic thermostats to provide early warnings of temperature increases or decreases can help maintain optimal conditions for corals.

About the author

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Marek Protasewicz

Reefkeeping has been my passion for over 10 years now. I love learning. The hobby has taught me many valuable lessons, patience being the best example. Combining work and passion is my path. I run Crazy Coral, a marine aquarium shop, for a number of years. Building this business from the scratch I learnt from my own mistakes at a heavy cost.
Later I managed a project aimed at development of methods for quick growth of Corals in non-natural conditions. The project was carried out by Get Sales, Poland. Presently, I am responsible for distribution strategy at Reef Factory, of which I am a co-founder. The company produces smart devices for marine aquaristics. The last projects I have been involved in are Social Reef and ReefPedia.

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