What Is the Best Temperature for Reef Tank?

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What is the best temperature for a reef tank? It’s probably one of the many questions that came into your mind when you were setting up your first reef tank.

The ideal temperature for a reef tank is in the 75 to 79 Fahrenheit (24 to 26 Celsius) range. Keep your water temperature as stable as possible. Large temperature fluctuations can stress your tank inhabitants and cause long-term health problems.

I know that was the first question that popped into my head when I started my reef tank. I live in a country where summers are hot, so keeping my tank temperature stable was a genuine concern.

Since the summer months approach at a fast rate, I need to figure out how to keep my tank temperature within the acceptable range.

If you have similar concerns, then this article will definitely help you. 

We will deep dive into subjects such as: What temperature is too hot for a reef tank, what temperature is too cold for a reef tank and what temperature is best for coral growth?

Without further ado, let’s get started!

What temperature is too hot for a reef tank?

Most of us keep different types of corals in our aquariums, and every species has its own acceptable temperature range. 

That’s why it’s challenging to determine one specific temperature when every inhabitant has different needs. However, we can make a wide temperature range and keep our reef tanks within it.

As mentioned earlier in this article, the ideal temperature range varies from 75 to 79 Fahrenheit (24 to 26 Celsius). However, different types of organisms have different thresholds of how well they can tolerate high temperatures.

For example, LPS corals come from deeper waters where the temperatures are cooler, and the flow is lower. When the temperature in our reef tanks rises above 82 Fahrenheit (27.7 Celsius), LPS corals will show their discomfort by not opening or fully extending.

On the other hand, SPS corals come from shallow waters where the temperatures are warmer, and the flow is higher. When the temperature in our reef tanks rises above 82 Fahrenheit (27.7 Celsius), SPS corals don’t show any signs of discomfort, quite the opposite. 

At those temperatures, they often show better growth. However, I wouldn’t go beyond 86 Fahrenheit (30 Celsius) for SPS because things may go south quickly at those temperatures.

Note: Keeping a stable temperature is better than chasing numbers. Don’t let your reef tank has large fluctuations.

What temperature is too cold for a reef tank?

Most reefers keep their reef tanks at a temperature around 77 Fahrenheit (25 Celsius). Arguably, it’s in the lower end of the ocean’s temperature range, but there is a reason for that.

Our aquariums are closed systems, and things can escalate quickly if we don’t pay attention to the temperature. For example, the solubility of oxygen and carbon dioxide changes with the temperature.

At higher temperatures, the oxygen is less soluble. It doesn’t affect the inhabitants in your reef tank in normal circumstances, but in crises where the temperature rapidly increases, the oxygen can be quickly used up.

When we keep our aquariums at a lower temperature, we have a better margin for error. However, I wouldn’t keep my reef tank below 75 Fahrenheit (24 Celsius) because at those temperatures, your inhabitants are not living but slowly dying.

What temperature is best for coral growth?

The best temperature for coral growth is 77 to 79 Fahrenheit (25 to 26 Celsius) for LPS corals and 79 to 82 Fahrenheit (26 to 28 Celsius) for SPS corals.

As you notice, that’s a slightly higher temperature compared to the temperature at which we keep our reef tanks. As the temperature rises, the metabolic rate of the corals in our reef tanks also rises.

It means that the corals use more oxygen, alkalinity, calcium, and all the other required elements for growth. In warmer waters, calcification occurs faster, therefore faster growth.

It’s why so many reefers see a better growth rate of their corals in the summer months when the temperatures are harder to control.

However, that doesn’t mean you should rapidly increase the temperature in your tank to see better growth of your corals. If you want to see better results without any casualties, do it slowly over a couple of weeks so the corals can acclimate to the new temperatures.

Final Thoughts

The temperature in our reef tanks is one of the most crucial water parameters, but it doesn’t get the attention it deserves. 

We are obsessed with measuring alkalinity, calcium, and magnesium while neglecting the temperature, which is the most important parameter along with the salinity.

People often don’t pay attention until the temperatures get high enough and notice corals declining in health.

Do yourself a favor and keep the temperature in your reef tank stable. Make sure that you have a reliable heater, a cooling device, and a thermometer that you can trust. 

It’s the only way to ensure that the temperature in your tank is always in the acceptable range.

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