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The alkalinity describes the acid-binding capacity of water and is an important basic parameter for a successful reef aquarium. It fulfils several essential tasks:

"Acid binders" such as carbonate and bicarbonate are consumed together with calcium in the skeleton structure of hard corals to build up calcium carbonate – which is poorly soluble in water. This alone explains the importance of alkalinity: if this is too low, no building of skeletons (and therefore no growth) can take place. Also, bacteria (such as nitrifying strains that break down toxic ammonium into nitrite and nitrate) require alkalinity to work efficiently. Alkalinity is therefore an important parameter even for sweet water fish tanks.

In our opinion, the optimal KH range is between 7° KH and 8.5° KH for saltwater aquariums. Higher values ​​should be avoided, as in combination with low nutrient levels tissue degenerations may occur.


Also, alkalinity forms the pH buffering system in seawater.

We measure the alkalinity with a titrimetric method with an accuracy of ± 0.1 ° KH.


Aluminum has no known biological functionality and can cause problems in corals and crustaceans at higher concentrations. The critical limit is 30 μg/l. Aluminum may enter the aquarium through the furnishing, cement products, contaminated salts or corrosive aluminum parts. Aluminum can be removed from the aquarium by exchanging water with aluminum-free water and by using iron-based phosphate absorbers.

We can precisely detect elevated levels of aluminum using the ICP-OES method in the Oceamo laboratory.


Antimony has no known biological function and can cause problems in the reef aquarium at elevated concentrations.

We can precisely detect elevated levels of aluminum using the ICP-OES method in the Oceamo laboratory.



Arsenic is primarily known as a toxin, but it probably fulfils essential functions for many living creatures (birds, mammals), which have not yet been thoroughly researched. In natural seawater, arsenic occurs at 3 μg/l, suggesting evolutionary adaptation of marine organisms to higher arsenic concentrations.


We can safely detect elevated concentrations of arsenic (from 3 μg/l) using the ICP-OES method in the Oceamo laboratory.


Barium occurs in seawater in low concentrations of about 13 μg/l. The biological significance of barium has not been clarified in corals, but studies of coral skeletons have shown that barium (in addition to calcium and strontium) is also deposited in the calcareous skeleton. Increased levels of barium may occur in aquaria due to furnishings (such as chip stones, ceramic products, etc.) as well as contaminated iron-based phosphate absorbers. It can be assumed that significantly increased concentrations may be toxic, whereby the tolerance varies greatly between different organisms. At strongly elevated concentrations, we recommend change of water to reduce the barium content. In the case of a barium deficiency, an increase to 13 μg/l is advisable in order to adapt the aquarium environment to natural water parameters.


Barium can be determined very well with our ICP-OES.


Lead is a toxic heavy metal and of no biological significance. The aquarium may be contaminated with lead due to old lead water pipes or contaminated water additives.


We can safely detect elevated levels of lead using the ICP-OES method in the Oceamo laboratory.


The function of boron in the reef ecosystem has not yet been completely clarified. However, it is essential for many organisms and too low boron levels often lead to deteriorated polyp scene in LPS corals. Similarly, low levels of boron inhibit the growth of macroalgae and result in a decreased pH buffering capacity of the water. However, high levels of boron are toxic, which is why we recommend keeping boron at a natural level of 4-4.5 mg/l.

Since boron is used up in the aquarium, occasional dosing is required.


Cadmium is toxic to the majority of organisms. Typical concentration in seawater is 0.05 μg/l.


We can reliably detect elevated levels of cadmium using the ICP-OES method in the Oceamo laboratory.


Calcium is a skeleton building element in hard corals, so a constant calcium content is essential for the healthy growth of SPS and LPS corals. The calcium value fluctuates greatly due to the consumption by corals, which is why regular dosing is necessary to keep the level constant. Calcium can also be measured well using test kits. We recommend measuring calcium at least once a week and adjusting the dosage of calcium accordingly.


We measure calcium with our ICP-OES. We recommend a calcium content of 430-440 mg/l with a salinity of 35.




Chromium is an essential trace element; however, it can be toxic at higher concentrations just like other heavy metals. Chromium occurs in seawater in a very low concentration of 0.5 μg/l. We recommend dosing a small amount of chromium regularly to safely prevent a shortage.


Iron is an essential trace element and iron-containing enzymes are involved, amongst other things, in transportation of electron and oxygen. It occurs in high concentrations in zooxanthellae (0.2-0.3 mg/g) and also in the skeleton of hard corals. The natural concentration is only a few micrograms per litre. An iron overload promotes the number of zooxanthellae but reduces the growth of stony corals. A shortage of iron has a growth-limiting effect.


We can reliably determine the iron content with our ICP-OES.


Fluoride occurs in seawater (35 psu) at about 1.2 mg/l. Fluoride is consumed on an ongoing basis and shortage can lead to reduced growth. We recommend regular fluoride content monitoring and adjustment. Overdoses must be avoided as fluoride is toxic in higher concentrations.


Fluoride cannot be determined by ICP-OES. We use our ion chromatography to quantify fluoride reliably from 0.1 mg/l.


Iodine is consumed in the reef aquarium by corals, algae as well as by phytoplankton and zooplankton. It is introduced by fish feed, but additional dosage is usually required to maintain the content at an optimal 50-70 μg/l (Salinity 35). Iodine deficiency is manifested by stagnation of growth as well as loss of colour. The consumption of iodine depends very much on the stock of animals in the aquarium and should therefore be analysed.



Potassium is a macro element and occurs in seawater at a concentration of about 400 mg/l. Potassium overdoses must be avoided as the nervous system of fish may be affected. Too low a potassium value can affect the colourfulness of SPS and may also be growth-inhibiting.

We measure potassium with our ICP-OES. We recommend a potassium content of 390-410 mg/l with a salinity of 35.


Cobalt is an essential trace element and component of vitamin B12. In natural seawater it occurs in an extremely low concentration of about 0.1-0.5 μg/l, therefore a quantification in the target range is uncertain with ICP-OES. We therefore recommend the regular dosing of trace amounts of cobalt in order to safely prevent a deficiency.


In the Oceamo laboratory, we can safely determine cobalt from 1 μg/l, and thus reliably detect unnatural and possibly critical enrichment.



Copper is an essential trace element and should therefore be present in seawater at a concentration of 1-2 μg/l. Copper is needed in key enzymes of the respiratory chain and can be detected in the tissue/skeleton of almost all corals. However, already a concentration of 10 μg/l of copper leads to growth problems, and subsequently to fading/dying of coral. This metal often enters the aquarium via copper water pipes and accumulates there. We recommend the analysis of your osmosis water using ICP-OES to exclude copper contamination.


Oceamo determines copper using ICP-OES. Concentrations from 1 μg/l can be reliably detected.


Lithium occurs in seawater in a concentration of 140-250 μg/l. Lithium plays an important role in the nervous system, although its exact function is unknown. Previously, lithium was used as an antidepressant. In humans, lithium deficiency is associated with mental health problems such as increased suicidal tendencies. We also recommend keeping lithium on a natural level in the aquarium, as it is very likely to be important for fish.


Oceamo determines lithium using ICP-OES. Concentrations from 1 μg/l can be reliably detected.


Magnesium is besides chloride, sulfate and sodium, the most abundant ion in seawater and therefore essential for many organisms. A consumption of magnesium is mainly caused by the growth of Coralline Algae. In comparison to calcium and KH, the consumption of magnesium is usually much lower, therefore a monthly dosage is usually sufficient.


We measure magnesium with our ICP-OES. We recommend a magnesium content of 1250-1400 mg/l with a salinity of 35 psu.




Manganese is essential for a variety of enzymes associated with photosynthesis and the decomposition of free oxygen radicals. It also plays an important role in DNA synthesis and the citric acid cycle. Manganese deficiency impairs a variety of biological processes and makes corals more sensitive to radiation stress. Manganese should be kept at a concentration of 2-4 μg/l.


Oceamo determines manganese by ICP-OES. Concentrations from 1 μg/l can be reliably detected.



Molybdenum plays a key role in many enzymes - such as nitrate reductase or sulfite reductase - as an electron carrier. - Therefore, its role is essential. In case of a molybdenum deficiency we recommend an increase to 10-12μg/l. Increased molybdenum values ​​indicate corroded steel parts. The cause must be quickly found and removed. The increased molybdenum value must be counteracted with frequent water changes.


Oceamo determines molybdenum using ICP-OES. Concentrations from 1 μg/l can be reliably detected.


Nickel is an essential trace element.


In the Oceamo laboratory, we can reliably determine nickel from 0.5 μg/l, and so diagnose under- or oversupply. Elevated nickel concentrations are critical in the seawater aquarium and can enter it through corrosive steel parts or magnets.


Nitrate is the oxidized form of nitrogen and thus the result of nitrification. Nitrate serves as a nutrient for corals, microorganisms and algae. In natural reefs nitrate is detectable only in low concentrations. However, the absence of nitrate in the reef aquarium may indicate nitrogen limitation, which is why we recommend a value of 1-5 mg/l. If no sensitive stony corals are kept in the aquarium, even a higher nitrate content is easily tolerated and even boosts the polyp structure of LPS and soft corals. Nitrate can only be detected very unreliably with commercially available test kits, as nitrite significantly interferes with the measurement.


We measure nitrate with our ion chromatography which gives a reliable reading. In order to achieve a low detection limit, we use a UV detector, which allows us to reliably determine nitrate even in concentrations of 0.01 mg/l.


Nitrite is an intermediate in the nitrification chain and a feared respiratory poison in freshwater fish keeping. In seawater, nitrite is significantly less toxic. Normally, nitrite is present in sea water in very low concentrations of less than 0.1 mg/l.


We measure nitrate with our ion chromatography which gives a reliable reading. It is usually difficult to determine nitrite in seawater samples by means of ion chromatography, since the nitrite signal is influenced by the chloride signal. With the UV detection we use, we can reliably detect nitrite, even at concentrations of 0.01 mg/l, regardless of chloride.



Phosphate is of essential biological importance to all living beings, and also forms part of DNA and RNA. In the reef aquarium we recommend a phosphate level of 0.02-0.08 mg/l. The range up to 0.12 mg/l is not optimal, but also occurs in natural reefs, and is tolerable. From 0.15 mg/l, however, there is a significant loss of colour and problems with calcification.


Values ​​below 0.02 mg/l suggest an acute phosphate limitation, which may be accompanied by a rapid loss of stony corals. Phosphate is mainly introduced in the reef aquarium by feed, and consumed by metabolism (corals, phytoplankton, algae, microorganisms). It is recommended to have a regular check of the phosphate level.


We measure the phosphate content of your water not indirectly via the phosphorus content by ICP-OES, but by colour reaction and a sensitive laboratory photometer. As a result, we only capture phosphate and give you a accurate reading of this important water parameter.



Mercury is a toxic heavy metal and of no biological significance. The aquarium can be contaminated with mercury by polluted water additives and salts. In addition, mercury is used in fluorescent lamps: the aquarium can be contaminated by breaking a T5 lamp with mercury.


We can safely detect increased levels of mercury (from 1 μg/l) in the Oceamo laboratory, using the ICP-OES method


Rubidium, like sodium and potassium, is an alkali metal. It is a significant component of natural seawater (~120 μg/l). Although its biological function is not scientifically proven, we recommend a natural rubidium concentration in the reef tank. Due to the high price of rubidium salts, it often does not occur in synthetic sea salt mixtures and should be supplemented.


Too high concentrations of rubidium are rare and result from contaminated sea salts or water additives.


In the Oceamo laboratory, we can accurately determine rubidium at 10 μg/l, and thus diagnose over- or undersupply well.


Salinity describes the salt content in seawater. For successful coral care the salinity must be kept as constant as possible, at 35-36 psu. This is achieved by automatic refilling with osmosis water and cleanly executed water changes.


Salinity is an important baseline value and the optimal content of all water components is related to the salinity measured. We measure the salinity with a conductivity cell, which is calibrated daily. This will give a reliable salinity reading.


Selenium is probably essential for all living beings. It occurs in the amino acid selenocysteine, fulfilling a role as radical scavenger. In seawater, selenium occurs in very low concentrations of 0.01-0.5 μg/l. Overdoses are thought to be toxic, with few data available for marine organisms. It can be assumed that sufficient selenium is added with the fish feed, therefore we do not recommend an additional dosage.


We can reliably detect increased concentrations of selenium (from 1 μg/l) in the Oceamo laboratory using the ICP-OES method.


Strontium, like calcium and magnesium, is an alkaline earth metal. Studies have shown that strontium is stored next to calcium in the coral skeleton of SPS and LPS corals. For this reason, strontium is consumed on an ongoing basis and we should aim for a natural content of 6-9 mg/l. Strontium can be individually compensated or continuously dosed as an additive to a calcium product as part of the Balling method.


Strontium cannot be properly detected with test kits. We determine the strontium content by means of ICP-OES with an accuracy of 0.1 mg/l.


Sulphate, along with chloride, is the most important anion in seawater. A low sulphate content indicates an ion shift, which can be caused by low-quality salt mixtures or adding balling solutions without regular water changes.


We measure sulphate with our ion chromatography and can thus reliably diagnose an ion shift.


Thallium is a toxic heavy metal and of no biological significance. The aquarium can be contaminated by polluted water additives and salts with thallium.


We can reliably detect increased concentrations of thallium (from 1 μg/l) in the Oceamo laboratory using the ICP-OES method.


Vanadium is an essential trace element and forms the blood pigment in many sea creatures. Also, vanadium is essential for higher algae and other marine organisms. The content in seawater is 2-3 μg/l. Depending on the aquarium stock, the consumption of vanadium may be subject to significant fluctuations.


In the Oceamo lab, we can determine vanadium by ICP-OES reliably, and thus diagnose well over- or undersupply.



Zinc is an essential trace element and is needed among others in the calcification, the breakdown of carbohydrates and the reduction of oxidative stress. The tissue of Acropora hard corals contains about 20 μg/g zinc. A zinc deficiency leads to a stagnation of coral growth and should therefore be remedied by dosage.


Oceamo determines zinc using ICP-OES. Concentrations from 1 μg/l can be reliably detected. The content of zinc in natural seawater is 2-5 μg/l. Significantly higher concentrations should be avoided as with all metals.


The content of tin is 0.5 - 0.8 μg/l in natural seawater, although the value can vary considerably depending on the water. Increased tin values ​​can cause significant problems such as the death of SPS corals.


Float glass, which is used in aquarium construction, has a tin-coated side due to the manufacturing process. For this reason, especially in newly established tanks increased tin values ​​and associated problems may occur.


With our ICP-OES we can reliably determine tin in the aquarium water from 1 μg/l.

pH value
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