Water quality is critical for biodiversity and life on our planet. Thus knowing the major water indicators and their characteristics is essential.

Water quality is one of the most critical ecosystem health indicators. Good quality water is essential for human life, wildlife, marine life, and maintaining biodiversity.

Many factors contribute to the degradation of water quality. Shipping and fishing activities, sewage and wastewater discharges, agricultural and industrial practices, fuel spillages, and global warming are all sources of pollution at sea.

Water pollution can have severe consequences for humans and the environment, including drinking water, fishing and aquaculture businesses, Marine Protected Areas (MPAs), wastewater treatment centers, river life, and coastal port towns. Therefore, water quality monitoring is critical for identifying potential environmental issues and developing effective preventative methods and system remediation.

The Key Indicators and Monitoring of Water Quality 

To comply with the standards, it's critical to understand, assess, and monitor the leading indicators of water quality and their primary parameters. Water quality indicators include dissolved oxygen, turbidity, pH, bioindicators, nitrate compounds, and water temperature, among other chemicals, physical, and biological qualities. Water samples are taken to test and monitor water quality, providing data on critical markers of contamination and changes in standard behaviour patterns.

Consider the most critical water quality indicators and how they affect water quality.

1. Dissolved Oxygen (DO)

Humans, plants, and animals all require oxygen in the water. However, if the water has an extremely high proportion of oxygen, it might pose serious challenges for life. It is critical to measure the amount of dissolved oxygen — the oxygen available to aquatic life. The amount of dissolved oxygen in streams and lakes is an important measure of water quality. Dissolved oxygen levels are affected by various factors, including the quantity of bacteria present and the temperature of the water.

Using fish as an example, research has demonstrated that all species and sizes of fish can live in water with dissolved oxygen levels between 9.5 and 12 mg/L. Fewer fish live below that level, and none can survive if it falls below 4.0 mg/L.

 Dissolved oxygen analyzer - Dissolved oxygen control

In industrial aquaculture, a high amount of oxygen is necessary for the water body. Fish require oxygen to carry out their physiological functions. Fish consume 3 kg of oxygen per day per tonne. To convert ammonia to nitrogen, biofilters need oxygen. 4.75 kg of ammonia nitrogen is consumed per tonne of fish released per day. Because more than 7.57 kg of oxygen is consumed directly and indirectly every day, a steady supply of dissolved oxygen (DO) for fish and biological filters is required for the water circulation treatment system to function properly. The DO parameter has to be kept above 60% of the water body's DO saturation or 5ppm for the fish to grow as quickly as feasible.

Dissolved oxygen levels fluctuate throughout the aquaculture process. The digestion of food by fish, for example, will rapidly reduce the amount of dissolved oxygen after feeding. At this point, the air pump must be controlled to increase the amount of aeration to maintain the dissolved oxygen level. When the demand for dissolved oxygen falls, the inflation rate must be adjusted to shorten the inflation period and save energy. As a result, automatic dissolved oxygen monitoring and prompt regulation of oxygen rise are critical.

The automatic dissolved oxygen control process follows: The dissolved oxygen sensor detects dissolved oxygen in the water and sends the information to the inverter. The frequency converter adjusts the current frequency in response to the received control result, adjusting the motor speed of the air pump or aerator and changing the amount of air inflated to satisfy the dissolved oxygen needs.

2. Turbidity and Total Suspended Solids (TSS)

Turbidity is a measurement of how clear and pure water is.

Total Suspended Solids concentration is used to determine turbidity levels (TSS). TSS are particles in the water that are larger than 2 microns in size, such as gravel, clay, silt, sand, and algae. Organic matter decays into a suspended solid from plants, animals, and algae. Insecticides, phosphorus, and heavy metals can all be found in high concentrations in suspended sediments. Lighter solids sink to the bottom of a body of water; if there are many solids, the surface water becomes hazy or less clear.

Assessing the Turbidity, TSS and Clarity 

All living things on the planet receive light, heat, and energy from the sun. At low or high levels, UV light can stop the photosynthetic process, causing long-term damage to the aquatic ecology.

Suspended particles, rotting vegetation, and other dissolved coloured substances make the water hazy and murky, reducing sunlight penetration and limiting aquatic life.

A rapid rise in turbidity and total suspended solids (TSS) signify soil erosion and point-source pollution, which introduces heavy metals and effluents into the water.

The scattered light is measured with a nephelometer at a 90-degree angle. The results are reported in Nephelometric Turbidity Units (NTU). After filtering and weighing the sample, total suspended solids are assessed in milligrams of solids per litre of water.

The Secchi disc is frequently submerged to determine the depth to which it is no longer visible (also referred to as the Secchi depth). This is a measurement of the water's cloudiness.

These water quality measuring devices aid in measuring water clarity and photosynthetically active radiation (PAR), ensuring a healthy environment for aquatic plants and animals.

3. Bioindicators

Bioindicators are organisms used to track an environment's health, such as the number of microalgae in water. Living creatures such as plants, animals, planktons, and microorganisms are natural and organic indicators of environmental contamination, offering vital information for assessing water quality and serving as a critical indicator of water pollution.

The amount of light, temperature, water and suspended solids in water all impact bioindicators in the environment. Changes in bioindicator composition, whether good or negative, are a valuable tool to assess the environmental impact of human activities on the health of our natural ecosystems.

4. Nitrates

Nitrogen is among the essential nutrients for all living things.

On the other hand, large nitrate concentrations can promote algal growth and lower the amount of dissolved oxygen in the water, killing fish and other aquatic life. This is commonly caused by the flow of human and animal waste, industrial pollutants, and agricultural activity. Humans are also affected by high nitrate levels. As a result, monitoring the nitrate level is critical for health promotion and marine life protection.

The optimal nitrate level depends on the species. Most freshwater species are protected by a maximum level of 2 mg NO3-N/l, while other creatures are protected by a maximum level of 20 mg NO3-N/l.

Ammonium ion-ammonia nitrogen Analyzer - Ammonia nitrogen control

For algae, nitrogen is an important macro element, and it's also a common nutrient that limits primary production in aquaculture environments, which has a significant impact on yield. Molecular nitrogen (N2), inorganic nitrogen (NH3, NH4+, NO2-, NO3-), and organic matter all exist in the water bodies of artificial aquaculture ponds (such as urea, amino acids, and protein). They are continually transforming and migrating in the water body under the impact of biological, non-biological, and human causes, and they are constantly undergoing dynamic cycles. The presence of nitrogen in water in the form of NH3 and NH4+ ions has the most significant effect on production. Algal growth requires the minerals NH3 and NH4+. 

Almost all algae can consume NH3 and NH4+ directly, swiftly, and preferentially. The drawback is that ammonia nitrogen prevents algae from using nitrite nitrogen (NO2-) and urea, and ammonia nitrogen consumes dissolved oxygen in water, especially in molecular form, during the conversion of ammonia nitrogen to nitrate. Fish and other aquatic creatures are very poisonous to ammonia (NH3). It can damage gill tissue, limit growth, aggravate fish illnesses, and have negative breeding and production consequences even at very low concentrations. The decomposition of nitrogenous organic materials in pond water and bottom sludge, as well as the metabolism of aquatic creatures, are the primary sources of ammonia nitrogen in pond water.

Artificial enormous volumes of bait and fertilization, especially in high-yield, high-input ponds, increase the amount of nitrogen-containing organic waste in the pond. The stocking density is high, biological metabolism is vigorous, and the amount of waste ammonia excreted increases. Because the pace of ammonia production exceeds the capacity of phytoplankton to use it, ammonia accumulates in the water.

The by-product of protein digestion in aquaculture is ammonia nitrogen, creating 2.2 pounds of ammonia nitrogen per 100 pounds of feed. The ionic (NH4+) and non-ionic (NH3) forms of ammonia nitrogen occur in water. Non-ionic ammonia nitrogen is particularly hazardous to fish and must be converted or removed.

5. pH scale

pH is a measurement of alkalinity that shows how acidic or basic a body of water is on a logarithmic scale. pH is measured on a scale of 0 to 14 and is expressed as a number. Low numbers show how acidic the water is, whereas more significant numbers indicate how basic it is. A score of 7 is considered neutral.

What causes the pH of the water to fluctuate? Acid rain, vehicular pollution, agricultural runoff, spills from accidents, sewer overflows, and other pollutants are among the factors. Significant fluctuations in pH scales can have negative consequences for water, fish, and aquatic life, making it another essential water quality indicator.

pH Analyzer - pH control

A commonly used economical and effective method for removing ammonia nitrogen in aquaculture water is establishing a biologically active filter. A nitrification reaction is carried out on the biofilm formed in the biological filter, which can convert the toxic substance ammonia nitrogen in the water. It is a less hazardous nitrate that is expelled from a water body to remove ammonia nitrogen. The nitrification process is primarily dependent on nitrifying bacteria, and the number of these bacteria is proportional to the amount of ammonia nitrogen removed. Experiments have demonstrated that the pH value directly affects the number of nitrifying and denitrifying bacteria and that alkaline water quality promotes nitrifying bacteria growth. The ammonia nitrogen removal effect can meet the present industrial farming standards for non-ionic ammonia 0.05 mg/L, nitrite 1 mg/L, and nitrate 200 mg/L when the pH value is 7.5.

6. Water Temperature

Water temperature is also a good predictor of water quality, as different aquatic creatures require different temperatures and water conditions to thrive. Other water quality characteristics, such as dissolved oxygen and organism vulnerability to parasites, pollution, and disease, will be affected by water temperature.

Another consideration is the time of year, as temperatures change with the seasons.

Temperature Analyzer - Temperature control 

Different fish require different temperatures to flourish. Fish grow quickly, have a high feed conversion efficiency, a strong physique, and a remarkable ability to resist fish infections when kept at the optimal temperature. The biological filter's effectiveness is also affected by temperature. The efficiency of ammonia nitrogen conversion will be harmed if the temperature is too low. The influence of temperature on cold-water fish breeding must be considered. However, the temperature is not the critical element affecting ammonia nitrogen in warm-water aquaculture. (Temperature is critical in some industries, such as salmon farming.)

Researchers and environmentalists can design and execute plans to conserve water bodies and foster biodiversity by measuring and monitoring key water quality indicators. The above-listed methods will assist you in determining the many criteria that influence water quality in freshwater and brackish water bodies.

Benefits of water quality measuring device

Basic on-site control, professional on-cloud wireless transmission control, and industrialized system management are the three approaches for real-time monitoring of fishery and aquaculture water environments (on-site display water quality measuring device: single parameter pH, dissolved oxygen, temperature, ammonia nitrogen ammonium ion or multiple options as per needs Parameter aquaculture instrument).

Starting with an on-site system, the deployment can progress to a cloud-based professional as needed. The fisheries authority can coordinate and upgrade to an industrialized system management type when a specified number of fish farming units are used in an administrative area.

The use of this technology will be a technological revolution in aquaculture, fundamentally transforming the history of farming based on the human experience. The scientific nature of aquaculture is improved by quantitative digital control of the aquaculture environment.

1. The stocking density was increased properly to produce a 30% increase in production by controlling the water body.

2. Reduce manual labour use and intensity, boost worker productivity, and cut expenditures by 20%.

3. Energy conservation and emission reduction and measurement and control to boost oxygen, feed, minimize bait feed, and cut water change times by 50%.

4. Increase revenue by 10% while improving product quality and reducing fish infections.

Thanks to this innovative technology, the comprehensive annual income will increase by more than 30%. In 1-2 years, the input cost can be recovered. It is a ground-breaking new technology application that deserves to be promoted.