Water Chemistry

Water chemistry is the lifeblood of a flourishing reef aquarium. It's about striking a precise balance in temperature, salinity, and a variety of elements such as calcium, magnesium, alkalinity, and nitrate and phosphate levels. These critical factors create an environment that mirrors the natural ocean habitat, setting the stage for corals, fish, and other marine life to thrive. Regular monitoring and careful adjustments ensure this delicate balance is maintained. While it requires diligence, the reward is a vibrant, healthy underwater ecosystem that adds a splash of nature's brilliance to your home.


Our Goal In The Coral Farm

Acceptable levels


24-26 °C (75-78 °F)

24-27 °C (75-80 °F)


1.026 SG, 35 ppt

 1.023-1.026 SG, 32-35 ppt





0 ppm

0 ppm


0 ppb

0 ppb


1-5 ppm

1-15 ppm


0.01-0.05 ppm

0.01-0.15 ppm


8.0 dKH

 7-12 dKH


440 ppm

 380-450 ppm


1320 ppm

 1200-1400 ppm


Temperature in a reef aquarium is a critical factor in ensuring the health and wellbeing of both corals and fish. Most tropical marine species, including corals and reef fish, thrive at temperatures between 75°F and 78°F (24°C to 26°C). Consistent temperatures within this range closely replicate their natural oceanic environments, promoting optimal metabolic function, growth, and coloration in corals. For fish, the right temperature supports proper digestion, immune response, and overall vitality. Sudden or frequent temperature changes can cause stress, leading to weakened immune systems, slower growth rates, and increased susceptibility to disease. Therefore, maintaining a stable and suitable temperature, along with regular monitoring, is key to creating a thriving reef aquarium.


Salinity, the measure of salt content in your reef aquarium, is vital for the wellbeing of both corals and fish. Much like their natural ocean environment, these organisms need a specific salinity range to perform essential biological functions. Typically, this sweet spot is around 1.023 to 1.026 specific gravity or 32 to 35 parts per thousand (ppt). When salinity levels swing too high or low, it can lead to stress, potentially impair health, and even cause mortality in your aquarium inhabitants. Therefore, it's crucial to routinely monitor and carefully adjust salinity to ensure a balanced, thriving environment, akin to the natural ocean ecosystem they're accustomed to.


A balanced pH is critical for coral growth as it affects the availability of carbonate ions, which corals use to build their skeletons. The ideal pH range is 8.1-8.4.

Your pH will typically swing by roughly 0.3 throughout the day, so measuring at any given point during the day will only give you a snapshot of what your pH is. To fully understand the pH levels in your aquarium it's best to measure with a probe over 24 hours.


Ammonia and Nitrite

In a healthy and well-maintained reef aquarium, the levels of both ammonia and nitrite should be zero. These compounds are toxic to all marine life, including corals and fish, even at low concentrations. Zero levels indicate that your tank's biological filtration system, also known as the nitrogen cycle, is working efficiently to convert harmful ammonia and nitrite into less harmful nitrate. This is achieved through the activity of beneficial bacteria that colonize your tank's surfaces and filtration media. Therefore, maintaining zero levels of ammonia and nitrite not only protects the health of your marine inhabitants but also signals a well-balanced and functioning aquarium ecosystem.

Nitrate and Phosphate

In a reef aquarium, nitrate and phosphate levels should be kept as low as possible to maintain the health of corals and other marine life, as well as to prevent unwanted algae growth. Ideal nitrate levels are generally below 10 ppm, though some corals can tolerate levels up to 20 ppm. For phosphates, aim for levels below 0.1 ppm. While some amount of nitrate and phosphate is necessary for the biological functions of corals and the symbiotic zooxanthellae they host, excess amounts can lead to explosive algae growth, which can outcompete corals for light and nutrients, and high nitrate levels may also reduce coral calcification rates. Therefore, maintaining low nitrate and phosphate levels is a critical aspect of maintaining a thriving reef aquarium.

While maintaining low levels is crucial for a healthy reef aquarium, aiming for zero isn't advisable. These compounds, in small quantities, are necessary nutrients for both corals and their symbiotic algae, zooxanthellae. Nitrates are used by corals for protein production and zooxanthellae for photosynthesis, while phosphates are essential for ATP production, a key energy source. Therefore, having non-detectable levels, or zero levels, can potentially starve your corals and inhibit their growth and overall health. It's all about balance; keeping nitrate and phosphate levels low, but not non-existent, supports a thriving reef ecosystem.

Major Trace Elements


Stability is a key element in maintaining alkalinity and overall water chemistry in a reef aquarium. Corals thrive best in a consistent environment and can be sensitive to significant fluctuations, including those in alkalinity. Constant swings in alkalinity can lead to stress, hindered growth, and potential bleaching in corals as it affects the availability of carbonates needed for their skeleton formation. Moreover, instability in alkalinity can also cause sudden changes in pH levels, creating further stress on the aquarium's inhabitants. Therefore, maintaining stable alkalinity, ideally within the range of 8 to 12 dKH, is fundamental for promoting healthy and vibrant corals, and for the overall well-being of the entire reef system.


Calcium is one of the fundamental elements that directly influence the health and growth of corals in a reef aquarium. As building blocks for their hard exoskeleton, corals extract calcium ions from the water and combine them with carbonate ions to form calcium carbonate, a process known as calcification. This not only facilitates the growth and repair of their skeletal structure, but also aids in their overall physiological health. Moreover, many other invertebrates and certain calcifying algae in the tank also utilize calcium for their metabolic functions. Therefore, maintaining optimal calcium levels, usually between 380 to 450 ppm, is a critical aspect of reef keeping. Inadequate calcium levels can lead to slow coral growth, pale coloration, and can compromise the health of the entire coral reef ecosystem.


In a reef aquarium, magnesium is an essential element that plays a significant role in the health and growth of corals. Magnesium is involved in several chemical processes, including supporting the utilization of calcium and carbonates that corals need to build their skeletons. It also helps maintain the ionic balance of the water and prevents the unwanted precipitation of calcium carbonate. Without sufficient magnesium, corals can experience slowed growth and have difficulties maintaining their overall health. Furthermore, low magnesium levels can make it challenging to sustain optimal calcium and alkalinity levels in the aquarium. Therefore, maintaining an adequate concentration of magnesium, typically between 1250-1350 ppm, is crucial for ensuring a thriving and vibrant reef environment.

Minor Trace Elements

While the focus is often on the major elements like calcium, alkalinity, and magnesium in a reef aquarium, minor trace elements also play a vital role in maintaining coral health. These include elements like iodine, iron, strontium, molybdenum, and zinc, among others. Each trace element serves a unique function - from supporting various metabolic processes, enhancing coloration, to aiding in skeleton formation. These elements are consumed over time by corals and other invertebrates and need to be replenished regularly. Although required in minute quantities, a deficiency in these trace elements can lead to poor coral growth, faded colors, and even reduced resistance to disease. Therefore, keeping a balanced concentration of these trace elements is essential for sustaining healthy, vibrant corals and overall biodiversity in a reef aquarium.

August 01, 2023 — Mitchell Ballou