Trans Instruments (S) Pte Ltd

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"The aquarium represents not only the most beautiful, but also the most educational and multi-faceted activity," said Kaspar Horst, author of "My First Aquarium".

Owning an aquarium is not just about feeding your fishes well and changing the water frequently, you should also consider many other aspects such as the temperature, acidity, conductivity, light, oxygen, hardness of the water, etc.

You should also monitor the water quality regularly so that the fishes will not be subjected to stress and fish-diseases can be prevented. In this page, we will be exploring the conditions of managing an aquarium.

First of all, the quality of the water in an aquarium is as important to fishes, as the air you breathe is to you. Even more so, because these life forms have to rely on you, the owner of the aquarium.

Testing & Water Quality

The only way for you to know how good or bad the water quality really is, is by testing it on a regular basis and keeping notes of the results in a diary.

Testing and keeping records is important in a basic reef aquarium. Moreover, keeping records will enable you to monitor how your tank "behaves". Any deviation in water quality parameters will be detected, as you are able to refer to previous readings.

The most important tests for your aquarium are pH, dissolved oxygen, ammonia and nitrite. Other tests that can be monitored are conductivity, temperature, hardness, nitrate, phosphate, residual ozone (if you are using an ozonizer), iron (if you keep macro-algae and fertilize), copper and total chlorine.


pH is a unit of measurement that describes the degree of acidity or alkalinity of a solution. It is measured on a scale of 0 to 14. Technically, pH is defined as the negative logarithms of the hydrogen ion activity or concentration.

pH = -log[H+]

The value of pH 7.0 represents neutrality. Below pH 7.0 is acidic and above 7.0 is alkaline.

Most of the fish species are happy in water within a range of pH 6.0 to 7.5, but others need water maintained to an even tighter specification. General conditions within the tank and particularly the level of carbon dioxide, have an effect on the water's pH levels. This makes it even more important that you monitor the water carefully, since a sudden shift in pH, even a small one, may present a danger to aquarium life. This is especially true in soft, acid-water tanks where there are more hydrogen ions present than in hard water.

In a well-planted tank, where there is a substantial uptake of carbon dioxide and nitrate by the plants, hydrogen ions will be steadily used up. There will be an increase in pH, unless you take steps to replenish carbon dioxide levels. In an aquarium that contains poor, or scant plant growth, however, the trend is towards a rise in potentially harmful nitrate levels and a decline in the levels of both pH and alkalinity.

Are you still measuring pH with litmus paper? Do you realise that this old method is INACCURATE and INEFFICIENT?

It's time to change to Trans-Instrument's high performance, lightweight, pocket size digital ECO pH+ tester. This compact tester is easy to use. Just turn it on and dip it into the sample solution.

Commercial adjusters, or buffers, which are based on sodium acid phosphate to increase acidity and sodium bicarbonate to increase alkalinity can be used to maintain the required pH range, should the need arise after testing.

Water Concentration

Water concentration varies in different ponds, lakes, rivers, canals and oceans, where fish thrive, breed and spawn.  For successful upkeeping of fish to display its full color and beauty, water concentration is one of the important factors.

Pure water is often related to soft water, where there are no minerals, salts or chemicals.  When water becomes concentrated, minerals, salts or chemicals are infused from ground water, mountain dew, rain water carrying minerals from soil and rock flows into lakes, ponds and rivers.  Each fish species has its desired water concentration at different stages of their growth, when they migrate to different places.

Therefore, reproducing such environments will induce spawning, breeding and encourage hatching of eggs etc.  This is where the professional aquarist takes pride of their success.

Trans-Instrument's DiscuSoft tester is specially designed for fresh-water fishes like the Discus, where water softness is important at different stages of its growth.  Each species of fish has similar behaviour, when the water concentration is right, they will glow in full color, mate and spawn.

Dissolved Oxygen

Oxygen is vital to the life cycle of aquarium inhabitants. It is essential to maintaining the health of the animals kept in the aquarium and for the aerobic bacteria necessary for the proper functioning of a closed aquarium system. A minimum concentration of 4 mg/L dissolved oxygen is adequate for most aquarium populations.

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 DO 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.


Fish have upper and lower limits of temperature tolerance and temperatures above or below this range can result in stress. A sudden temperature change may lower the disease resistance of fish and increase their susceptibility to infections.


Hardness is originally referred to the ability of water to precipitate soap. The precipitation is largely a function of the concentration of calcium and magnesium in water. Ions of several metals and the hydrogen ions may cause the precipitation. Hardness has now come to mean the total concentration of calcium and magnesium ions expressed in terms of parts per million (ppm) of calcium carbonate.

Classification ppm of calcium carbonate
Soft water
Below 50
Medium Soft water
50 - 100
Slightly Hard water
100 - 200
Moderately Hard water
200 - 300
Hard water
300 - 540
Very Hard Water
Above 540

Calcium and magnesium are important nutrients for aquatic plants. For planted aquarium tanks, it is better to have slightly hard water of 150 - 200 ppm. Most fish will do quite well in slightly to moderately hard water but for the development of the eggs, it is critical to have soft to medium soft water.


Fish release urine and excrement just as all other living organisms do. In their natural habitat, these "waste products" are quickly washed away or broken down. In the aquarium however, this task is left to the bacteria which are essential in the process. In a freshly equipped tank, the bacteria do not yet inhabit or are not sufficient.

The break-down of the waste process follows a sequence:

Urea ---> ammonium/ammonia ---> nitrite ---> nitrate (End product)

In the intermediate stages, ammonia and nitrite are toxic to fish in small quantities. You therefore, have to be especially vigilant in the aquarium's early phase.

Nitrite levels of under 0.2ppm are acceptable to most fish. Levels above that indicate an abnormal break-down of nitrite. If the nitrite levels are higher than 0.5ppm, the fish will die.

With a new aquarium, it is essential to closely watch the fish on a daily basis. If you notice them displaying an abnormal behaviour, test the nitrite levels. Change the water if the nitrite levels are 0.2ppm and above.

Ammonia/ammonium level is dependent largely on the pH value. The higher the pH value the more toxic ammonia, is produced from ammonium. At pH 7, the total amount consists as non-toxic ammonium. At pH 8.2, about 10% of the tested amount is toxic ammonia. At pH 9, this percentage climbs to 50%. By maintaining a neutral pH level in the aquarium, the danger of ammonia is removed.


Nitrate is a vital source of nutrition for plants. But aquarium plants are by nature not accustomed to large quantities of it. In natural environments, they survive on very low levels of nitrogen in the form of ammonium and a trace of nitrate. With high levels of nitrate in the tank, the danger of attracting unwanted algae rise especially the dreaded blue and beard algae which prefer to feed on nitrate.

Oxidation Reduction Potential

Oxidation reduction potential (ORP) can be used to indicate the oxidation level in water. ORP represents the balance of electrons in water. Water with a high ORP is of high quality, containing much surplus oxygen and complete mineralization of all waste organic material. If the ORP is too low, there is a chance that oxidation and mineralization may not occur at all and the waste products accumulate to become toxic substances.

A balanced salt-water aquarium should have a reading of between 350mV to 400mV. In freshwater aquariums, readings of 250mV are sufficient. Trans-Instrument's Senz Redox is an ideal tool to measure the ORP value.

Lighting in Aquarium

Lighting is one of the important areas of concern for the home aquarist in ensuring a healthy, well-balanced and flourishing aquarium. Plants are quite demanding in their light requirements. Incorrect lighting may favour the growth of certain undesirable algae at the expense of other algae and plants you want to encourage.

Types of light
The human eye responds to the aquarium lit with a yellow/green light because it appears warmer and more appealing. Plants, however, prefer the red/blue ends of the spectrum. Although some light is absorbed in water, the average aquarium is not deep or cloudy enough to make an appreciable difference. Manufacturers of lights have responded to the different needs of aquarists by producing an extensive range of bulb types and qualities.

Measuring light
Assessing the quantity of light without the aid of a light meter is very subjective. You need a light meter to measure the intensity accurately. Light from a particular source is measured in lumens. But for the aquarist, it is more important to know the amount of lumens per square meter or "lux" of the water surface area than just simply the light's total output.

Light requirements
The actual requirements of many aquatic plants vary tremendously: some have evolved to grow in dim light, while others are habituated to the full glare of an equatorial sun. Although many plants are adaptable, nearly all have preferences for specific lighting levels. Providing lighting levels outside of these tolerance ranges for extended periods may adversely affect growth.

Lighting Suitability
Appearance  Intensity Suitable for
Subdued <500 lux  Crytocoryne, Vesicularia
Moderate 500 - 1,000 lux Anubias, Echinodorus, Nomophila, Sagittaria
Quite bright 1,000 - 1,500 lux  Bacopa, Ceratopteris, Egeria, Ludwigia
Bright >1,500 lux Cabomba, Hygrophila, Microsorium, Myriophyllum, Synnema, Vallisneria
Very bright 6,000 - 8,000 lux  Anemones 
Dazzling 12,000 - 16,000 lux  Macroalgae (e.g. Caulerpa)
Very dazzling 15,000 - 20,000 lux  Most corals (except for most red corals and sponges, which prefer shade)
Lighting Balance

As you can see for the table above, marine organisms tend to prefer intense levels of light. Freshwater plants, however, usually prefer light levels lower than those of algae. The maximum rates of photosynthesis occur at 10 to 20,000 lux for many common species of vascular plants and yet algae continue increasing until 35,000 lux (values that actually inhibit plant growth). This means that excess illumination, either from the aquarium lights or from sunlight, may favour algae growth over plant growth.

It is also important that you replicate the natural diurnal period expected by fishes and plants, so light the aquarium for only 10 to 16 hours per day. To avoid stressing the fishes, never switch the lamps on and off suddenly; switch off the aquarium lights a few minutes before turning off the room light and switch the room lights on before the tank lights. Some marine aquarists leave a low-wattage red light on the tank all night. This is because in nature, marine fishes rarely experience total darkness.

The standard level of fluorescent light required is in the region of 0.016 to 0.022 watts per (0.10 to 0.14 watts per sq. in). For marine tanks, an Actinic Blue 03 tube should accompany the fluorescent tube. For coral reef tanks, metal halide lamps are better than fluorescent tubes. Use as recommended by the manufacturer.

Not sure of the measurements of your aquarium's light? Now you can use Trans Instrument's AquaLiteCheck tester. Not only does the meter have high performance, good repeatability and high accuracy, it also has a wide range of light measurements up to 50,000 Lux.