If you run a marine aquarium, you already know how important it is to maintain the right chemical balance in the water. Today we’ll talk about strontium – an element that many beginners overlook, yet it can make a huge difference in the growth, color, and overall health of your corals. Strontium isn’t as famous as calcium or magnesium, but without it reef life won’t thrive as it should. In natural seawater, strontium levels hover around 8-10 mg/l, but in our tanks it gets depleted quickly.
Why is strontium important in a marine aquarium? #
Strontium works much like calcium. Hard corals such as SPS (Small Polyp Stony) and LPS (Large Polyp Stony) use it to build their skeletons. It’s part of aragonite, the main building block of coral reefs. Without enough strontium, corals grow slower, their skeletons become brittle, and their colors fade.
It’s not just about aesthetics-strontium also improves calcium absorption, meaning your corals make better use of available nutrients. It supports the growth of coralline algae and soft corals, both of which help filter the water. In a closed aquarium system, where there’s no natural replenishment from the ocean, strontium is consumed quickly. Protein skimmers and filtration media remove it along with other impurities. That’s why supplementation is crucial, especially in tanks with a dense reef setup.
Studies show that maintaining proper strontium levels strengthens coral resistance to parasites and stress, which in practice means fewer health issues.
Signs of deficiency and excess in reef tank #
Strontium deficiency – how to recognize it? #
At first, strontium deficiency shows up subtly. Corals stop growing, their polyps don’t fully open, and colors-especially blues and greens-start to fade. Skeletons become thin and fragile, and in extreme cases, dead patches may appear. This is often mistaken for calcium deficiency, but if calcium levels are fine and problems persist, it’s worth testing for strontium.
The most common causes? Lack of supplementation in tanks with high coral demand, infrequent water changes, or using salt mixes low in trace elements. In tanks without dosing, strontium can drop below 5 ppm, which disrupts calcification-the process corals use to build their skeletons.
Strontium overdose – what to watch out for? #
Excess strontium may enhance trouble. Above 15 ppm, you may notice deposits on equipment, cloudy water, and corals turning gray or losing tissue. Too much strontium disrupts the balance with calcium and magnesium, leading to lower alkalinity and unstable pH.
Common causes include overdosing supplements, using salt mixes high in strontium, or inaccurate test readings. In extreme cases, it can even encourage the growth of nuisance algae. Because strontium is chemically similar to calcium, organisms can “confuse” the two, and excess strontium blocks normal processes.
How to supplement strontium in a marine tank #
Strontium supplementation is a must in a reef aquarium. It is best to use ready-made preparations that are safe and easy to dose. For example, Strontium from Aquaforest is an effective supplement containing highly concentrated strontium. Strontium, after calcium and magnesium, is one of the most important elements needed for the proper growth of hard corals. It supports the construction of the skeletal tissue of hard corals and significantly improves their absorption of calcium. It also supports the growth of soft corals. In a closed aquarium system, the skimmer and filter media remove deposits of strontium from the water, so its supplementation is necessary. In order to ensure that conditions in the aquarium are as close to natural as possible, the preparation is enriched with the addition of barium, which is also found in seawater. By maintaining the right proportions, Strontium effectively replenishes the deficiencies of strontium and barium in aquarium water and guarantees a proper balance of these elements. The level of strontium in a reef aquarium should vary between 5 and 15 ppm.
How to dose strontium #
Recommended dosage: 1 drop per 100 liters (26 gallons) of water daily. Adding 10 ml of Strontium increases the level by 1 mg/l (ppm) in 100 liters of water.
Keep in mind that every aquarium is unique – daily dosing depends on coral density and individual demand. Always start with half the recommended dose and monitor results. Within a week, you should see improved coral growth and polyp extension.
Using a dosing pump helps automate the process, but always add the supplement to the sump water to prevent localized overdosing.
Strontium level balance with other elements #
Balance is everything in reef keeping. Strontium works hand in hand with calcium (Ca) and magnesium (Mg). The recommended Sr:Ca ratio is about 1:1000, as in the ocean. Magnesium stabilizes both calcium and strontium, preventing them from precipitating out of solution.
Barium, included in Aquaforest Strontium, further supports calcification and prevents corals from graying out. Potassium (K) should stay about 20 ppm lower than strontium since it affects coral coloration.
If you’re using the Balling Method, strontium can be added to the calcium container. But beware: low magnesium can block strontium absorption, leading to deficiencies even if you’re dosing correctly.
Regularly check strontium levels and adjust supplementation based on your results.
Why choose Aquaforest Strontium? #
Strontium from Aquaforest is no ordinary additive – it is a concentrated, safe supplement that mimics natural seawater. Its use allows you to quickly and effectively raise Sr levels in your marine aquarium to an optimal value. With the addition of barium, it provides a complete balance, which means healthier corals, more intense colors and fewer problems. It is easy to use, does not affect pH and is economical – a 50 ml bottle lasts for months with a small aquarium. Users on forums praise it for its quick effects: corals grow faster, polyps are more open. If you have a reef, it’s an investment in the stability of the tank.
Importantly: the chemical composition of Strontium was developed, among other things, to facilitate a comprehensive method of keeping a marine aquarium (especially with a view to replenishing deficiencies and sudden drops).
It is safe for fish and other organisms in the aquarium.
Strontium in a marine aquarium – frequently asked questions #
- Do I need to dose strontium if I do regular water changes?
Not always. In small tanks with a light coral load, high-quality salt may be enough. But in SPS-dominated tanks, demand is high, so supplementation is usually necessary. Always rely on water tests. - What if I overdose strontium?
Do a 10% water change with a low-Sr salt mix, and repeat every 2 days until levels stabilize. Avoid sudden changes, as they stress corals. - Does strontium affect fish?
Not directly. Fish don’t need strontium, but a stable chemical balance benefits the whole ecosystem. - Does strontium help with algae?
Indirectly, yes. It supports coralline algae, which outcompete nuisance algae.
Summary #
Strontium is the silent hero of the marine aquarium. With the right supplementation, like using Strontium from Aquaforest, your corals will grow healthy and colorful. Test and enjoy the view – aquaristics is a passion, and details like this make all the difference. Good luck!