In this article, we will go over the most important additives and supplements for reef tanks. In previous blogs, we’ve discussed the most important water parameters and tests:
- Water Quality for Reef Tanks (Part 1): The Most Important Parameters
- Water Quality for Reef Tanks (Part 2): The Most Important Tests
So, now it’s time to discuss how to maintain these parameters and what should be used to help achieve the best growth AND color from our corals. We will go over why these additives and supplements are important, what the optimal ranges are and how to maintain them.
Click on a parameter below to learn more:
Salt (Salinity) | Alkalinity | Calcium | Magnesium | Strontium | Iodine | Iron | Potassium
Salt (Salinity)
Why It’s Important: Corals need a specific salt-to-water ratio to survive.
Optimal Range / Levels: 1.024 – 1.026 sg (specific gravity) / 32 – 35 parts per thousand (ppt); salt should be mixed to match the current salinity of your aquarium.
How to Maintain the Proper Levels: Regularly scheduled water changes at the same time every month, using a high-quality salt mix.
How to Choose a Good Salt: Choose a salt specifically created for a reef tank, as they generally have higher levels of alkalinity and calcium. Many reef salt mixes also contain important minor and trace elements.
Alkalinity
Why It’s Important: A stable, non-fluctuating alkalinity helps keep the pH in your aquarium stable and improves coral health and growth. Since it is consumed by corals and not replenished naturally, it needs to be added back to your tank on a regular and consistent basis.
Optimal Range / Levels: 7-10 dkh
How to Maintain the Proper Levels: Alkalinity can be dosed manually or automatically on a set schedule using a dosing pump (recommended). Before starting, test the current alkalinity levels in your reef tank and then dose accordingly to the preferred level, making sure not to raise the alkalinity by more than 1 dkh in a 24 hr period. Continue to test daily for 3 days, adding the amount needed to keep levels in the preferred range. After 3 days your tank should have consumed nearly the same amount each day. That will be your daily dosing regimen going forward. Continue testing at least once a week to ensure the current dosage is maintaining the proper level. Keep in mind that alkalinity can be consumed rapidly when new hard corals are added and when there is a rapid amount of growth from sps and lps corals.
Commonly available options for dosing alkalinity:
- Sodium Bicarbonate
- Soda ash
- Kalkawasser
- ATI Essentials Pro
Calcium
Why It’s Important: Calcium is vital for growing corals with a skeletal structure, clams and coralline algae. It is rapidly consumed in a reef tank with hard corals and needs to be replenished regularly.
Optimal Range / Levels: 400-450 ppm (parts per million)
How to Maintain the Proper Levels: Calcium can be dosed manually or automatically on a set schedule using a dosing pump (recommended). Start by testing the current calcium level in your reef tank, then calculate the dosage to achieve the preferred level. Test for 3 straight days, adjusting the dosage to keep levels in the preferred range. After 3 days, your tank should have consumed nearly the same amount each day. That will be your daily dosing regimen going forward. Test at least once a week going forward to ensure the current dosage is effectively maintaining the proper level. Calcium can also be consumed rapidly when new hard corals are added and when there is a rapid amount of growth from sps and lps corals causing a higher demand for calcium.
Magnesium
Why It’s Important: Proper magnesium levels help prevent precipitation of calcium carbonate and helps maintain the proper balance of calcium and alkalinity. If you are having trouble maintaining proper calcium and alkalinity levels, the most common culprit is low magnesium levels.
Optimal Range / Levels: 1250-1500 ppm (parts per million)
How to Maintain the Proper Levels: Magnesium should be tested at least once every two weeks. It can be added manually or dosed with a dosing pump.
Strontium
Why It’s Important: Strontium, much like calcium, is used to help build coral skeletons and coralline algae. The regular addition of strontium has been found to increase coral growth.
Optimal Range / Levels: 8 ppm (parts per million)
How to Maintain the Proper Levels: Strontium is found in many salt mixes, but it is depleted rapidly in an aquarium. Testing should be done every two weeks and is typically dosed manually using the manufacturer’s recommendations.
Iodine
Why It’s Important: Iodine is an essential element used by corals for the synthesis of pigments – allowing them to adapt to varying light conditions. It also helps protect coral tissues from UV radiation. Invertebrates like crabs and shrimp incorporate iodine into their exoskeletons to help molt and to form new exoskeletons as they grow.
Optimal Range / Levels: 0.06 ppm (parts per million)
How to Maintain the Proper Levels: Testing for iodine is recommended every 2 weeks. Regular dosing of iodine is recommended. However, overdosing can be toxic, so it is absolutely critical to test before adding any amount to your reef tank.
Iron
Why It’s Important: Iron is used to help enhance the green coloration in many sps corals. If green sps corals begin to look a pale or faded, chances are they are low on iron. Iron is also used by chaeto and macroalgae in refugiums.
Optimal Range / Levels: 0.1 – 0.5 mg/l (milligrams per liter)
How to Maintain the Proper Levels: Iron can be tested for, but the best way to tell if your reef tank needs iron is visually. If green colored sps corals or macroalgae look pale, then they may need some iron added to the system. The easiest way to dose is to add a little bit every 4-5 days until the green is more intense.
Potassium
Why It’s Important: Potassium is used both in the skeletal and cellular process of stony corals and also used by zooxanthellae. Although commonly misread as other problems, some studies have shown that potassium deficiency in a reef tank may cause tissue necrosis starting at the base of the coral, poor growth and pale or bleaching tissue. On the flip side, excessive potassium can cause tissue necrosis at the tips of corals, causing tissue to peel and flap around the bare skeleton, darkening of tissue due to rapidly increasing zooxanthellae and slower growth.
Optimal Range / Levels: 380-420 mg/l (milligrams per liter)
How to Maintain the Proper Levels: Potassium is generally maintained with regular water changes, although it can be depleted rapidly with carbon dosing. If regular water changes are not performed or if you are carbon dosing, regular dosing of potassium will likely be needed following the manufacturer’s recommended dosing regimen.
Maintaining your reef tank may seem like a complicated science project with all the testing and addition of different additives and supplements to maintain the correct parameters. But once you figure out what works best for you, it becomes a much easier task.
Looking for an easy way to maintain these parameters and other key elements? Our ATI Essentials Pro is an easy to use, 2-part dosing system that contains 28 major and trace elements. When used properly, it can help maintain all these parameters as close to natural seawater as possible.