Trans Instruments (S) Pte Ltd

5 Jalan Kilang Barat #06-04/05 Petro Centre 159349 Singapore ,

"Aquaculture is the culture of animals and plants in water."

Broad classes of organisms grown include fish, plants, reptiles, crustaceans and mollusks destined for food or non-food markets. Production systems include ponds, tanks, raceways, net pens, suspended cages, clutch bars, net bags and the bottom nets used on submerged lands for clam production. Water types range from fresh to brackish and to salinities exceeding seawater.

Many aquarists, retailers, breeders and wholesalers have recognized the direct relation of water quality to the health and longevity of the aquatic environment. As such, aquarists are more aware of the importance of water testing.

Routine water testing of parameters such as pH, dissolved oxygen, conductivity, hardness, nitrate, phosphates and temperatures, reinforce disease prevention. This is so because any stressful environmental conditions can be detected and analyzed easily and quickly.


pH is a measurement of the degree of acidity or alkalinity of water. It is measured on a scale of 0 to 14.

General health and well being of the culture stock can be attributed to the pH level. Every cultured species has a preferred pH range in which it will grow best and breed.  A pH level near to their native environment is the best. 

Maintaining a correct pH is a constant concern for the aquaculturist. pH adjustments require several careful dosages over a period of time instead of a single large dosage. Large pH fluctuations can cause shock to all species and result in heavy casualties.

A well maintained pH level will result in less stress and thus reducing sickness and deaths.

Trans Instrument's Eco pH+ tester is ideal for aquaculture use due to its simple usage and rugged design . It is water, drop and shock resistant.  Even in the event of accidental drop into water, the tester will float to enable immediate retrieval.

For professional technicians who want higher accuracies, choose the WalkLAB microprocessor pH meter HP9010. These durable meters come with replaceable pH electrodes and can be replaced separately when expired.

Water Concentration

The dissolved mineral salt contents and chemical loading are unseen substances in the cultured water tank.  Like sugar concentrate or syrup, water has different degrees of concentration.  High concentrations result in unbearable living environments for any water thriving species.  This can result in stress, due to induced expel of excessive water caused osmosis imbalance, which ultimately results in death to aquatic life.

For fresh water species, some require specific water concentrations to breed, while others need soft water to spawn. The DiscuSoft and Crystal Shrimp Pro testers are specially designed to measure water softness.  They are used by professionals to induce breeding of certain fish species and are a quick way to measure water softness.

Salt also alters water concentration in many ways.  It has been used as a way to prevent parasites and for the purpose of quarantine of imported fish.  For hospital tanks, higher water concentration helps fish to absorb medication more readily, thus improving healing and recovery from sicknesses.  The KoiMedic tester is designed to measure the right amount of salinity for fish under quarantine.

For marine aquaria, sea water concentration is critical for marine lives. Hydrometers to measure the specific gravity of sea water is often used but has its limitations.  Trans Instrument offers the economical Salinity Refractometer as well as the digital Marine Salt Testa for this very purpose.

Dissolved Oxygen

Dissolved oxygen in aquatic culture is one of the most critical parameters. All commonly cultured species need oxygen to survive. A concentration of 5 mg/l dissolved oxygen is adequate for most cultured organisms. The actual levels of oxygen needed by particular species vary greatly with the size of the animal, the temperature and the stress the animal suffers from.

Many factors affect the dissolved oxygen content of water and frequent testing for dissolved oxygen is important. Temperature affects the oxygen-holding capacity of water. As the temperature increases, the amount of dissolved oxygen decreases.

With Trans Instrument's WalkLAB Digital Dissolved Oxygen meter and Professional Dissolved Oxygen meter HD3030, oxygen measurement can now be made in situ. There is no need of a sampling device and a flask to retain water in its natural state for later analysis in the laboratory. The meter has high performance, good repeatability and high accuracy. It measures 0 to 20 mg/l.


Temperature is one of the most important environmental variables for all aquatic organisms. It influences the oxygen content of the water, the primary product which is the source of food in the open sea and affects the reproduction and growth of all species.

Different species have different upper and lower limits of temperature tolerance and temperatures above or below this range can result in stress. Sudden temperature fluctuations may lower disease resistance of the cultured organisms and increase their susceptibility to infections. Although some animals can partially regulate their body temperature, the culturist may still try to maintain an optimal growth temperature so that all the organisms' energy can go toward producing more tissues rather than staying warm so that it can remain alive.

A rise in water temperature increases the metabolic rate of aquatic organisms and therefore their energy requirement.  Trans Instruments' Arowana Pro and Crystal Shrimp Pro incorporate temperature measurement as part of the measuring system.


Hardness is the total concentration of calcium and magnesium ions expressed in terms of parts per million (ppm) of calcium carbonate in water. Water containing small concentrations are referred to as "soft", those containing large concentrations are known as "hard". Calcium is important in water systems since it is taken up and used in the bones of fish and in the shells of crustaceans and mollusks.

Soft water cannot be used in the culture of crawfish because the exoskeletons will be too thin to offer the sort of protection that the animals need. Calcium is also important in the hatching of some fish eggs. The eggs of the marine dolphin fish, Coryphaena for example, will not hatch in calcium free seawater and magnesium seems to be important for its development, especially immediately before and after hatching. The DiscusSoft and Crystal Shrimp Pro testers are specially designed to measure water softness.


Dissolved mineral salts and organic matter constitute the reserves of nitrogen, phosphate, and silicon, essential for the growth of phytoplankton. Their deficiency is particularly important in the open sea and where phytoplankton production represents the only source of available food. Soil erosion, urban and agricultural waste, and the decomposition of organic detritus represents the principal sources of introduced nitrogen and phosphorus in the marine environment. When the quantities introduced are high, they may cause an explosion in the multiplication of phytoplankton and other algae,  major imbalances in the coastal ecosystem, known as eutrophication.


All organisms provide a source of organic nitrogen through their excretory products, by-products of metabolism, and the breakdown of dead cells and tissues. In most water, there is a natural nitrogen cycle that will make organic and inorganic nitrogen into forms which can be directly assimilated by phytoplankton and plants.

In the nitrogen cycle, harmful ammonia and nitrite are constantly converted into less harmful nitrate, which in turn is used by plants and algae for food. Biological filtration replicates this cycle. The level of ammonia in the waste produced by living organisms which are kept in a confined environment such as intensive rearing systems can be significant. In certain circumstances, levels may be toxic; these vary with species and depend on pH and the oxygen content of the water. In general, the level of ammonia which does no harm to aquatic organisms is less than 0.1mg ammonia in the form of NH3 per liter.

Besides dissolved oxygen, oxygen reduction potential (ORP) can be used to indicate the activity of the Nitrogen cycle. ORP represents the balance of electrons in water. Water with high ORP value is of high quality, indicating a good amount of nitrifying bacteria for the mineralization of organic waste. If the ORP is too low, there is a chance that oxidation and mineralization may not occur and the waste products accumulate to become toxic substances. Trans Instrument's Senz Redox is an ideal tool to chart the trend of ORP fluctuations.


Phosphorus, usually in the form of orthophosphate (PO4-3), is also a critical nutrient for plants. Phosphate in water comes from the mineralization of decaying cells and organisms as well as from human activities (agricultural, industrial and domestic).

High levels of nitrogen and phosphate result in an increase in the number of weeds and algae. At night, the plants use oxygen and the dissolved oxygen in a fish pond can fall to lethal levels. During the day, plants will remove carbon dioxide from the water, allowing the pH to rise and cause the ammonium to be converted to more toxic ammonia.