Healpful Tips

Aquarium Water Quality & Parameters

By far the most important element in a fish’s life is the water in which they live in. If you want to be successful in keeping tropical fish (freshwater or saltwater) then you'll need to know how to test your aquarium water.

There are many aquarium test kits, chemically or electronically to choose from. The type of test kit explained here has chemical liquid droppers. You dispense the liquid (certain number of drops) into a test tube with your aquarium water, following the manufacturer’s instructions. You usually need to shake the tube to mix the chemicals with the water and wait a few minutes for the test to develop. You then match the color of the water in the test tube against a test card to get your final reading. Below are some brief explanations of various water parameters (based on your type of aquaria) that you need to test and correctly maintain in order for your fish to thrive.

Alkalinity -

Alkalinity and pH are distinctly different from each other, although their definitions and functions can be easily confused. For those of you as uninformed about water chemistry as I was when I first began, alkalinity is essentially a measurement of water's ability to neutralize acids. It is a measure of the buffering capacity of a system while pH is basically the measurement of the concentration of hydrogen ions in water, in terms of acidity or alkalinity. The alkalinity of water regarding pH issues merely refers to the basic end of a pH scale (alkaline) in contrast to the acidic end of the scale and does not reflect the buffering capacity of a system. It is easy to believe that water with alkaline pH is likely to be high in alkalinity (buffering capacity). However, this is not necessarily true. Water with a high pH, but a low alkalinity is regarded as unstable. Such water will quickly decline in pH with the natural accumulation of organic acids in aquarium systems.

Ammonia -

Ammonia is one of the most studied chemicals in aquaria, and the details of its uptake, excretion and mechanisms of toxicity continue to occupy many research scientists. Because of its high toxicity, it is critically important in both freshwater and marine systems. In fact, it is one of the few important chemical issues that marine and freshwater aquaria share. Nevertheless, misunderstandings abound about ammonia's sources, nature and toxicity, which may not be recognized by many reef aquarists.

Boron -

The importance of boron in marine aquaria is a subject that is not often discussed by hobbyists, despite the fact that many people dose it every day as part of their alkalinity supplements. In fact, most commentary on boron derives from manufacturers that are selling it in one fashion or another as a "buffering" agent. Unfortunately, these discussions nearly always lack any quantitative discussion of boron or the effects that it has. You will be surprised at how much pH buffering boron actually provides. You may, in fact, be surprised to learn that boron actually contributes only a minor fraction of the buffering of normal seawater.

Calcium -

Calcium is one of the most talked about ions in reef tanks. It is critical for the formation of a variety of structures, including the skeletons and shells of many corals and other organisms. Calcium is abundant in various supplements, biological structures, rock and sand, and affects other ions like phosphate, and how organisms take up and deposit calcium.

Copper -

Copper is often used to treat many parasitic infections in fresh and saltwater fish. To be effective, the copper concentration in the aquarium must be maintained at the therapeutic level for several weeks. Frequent testing is required to monitor the copper level in the aquarium. Some fish species are very sensitive to copper treatments. Copper should not be used or be evident in aquariums with invertebrates, including snails, shrimp, crayfish and corals, as well as in freshwater aquariums or ponds with plants. Tap water may contain copper leached from pipes and, ultimately, it can accumulate in the aquarium.

Iodine -

In the "hobbyist" sector of reef keeping, Iodine has been found to benefit soft corals, assist in calcification in stony corals, and enable crustaceans to molt properly. Iodine can also be used as a "dip" since it has antiseptic qualities as well.

pH -

is basically the measurement of the concentration of hydrogen ions in water, in terms of acidity or alkalinity, in other word is the scale used to measure the acidity or alkalinity of water. The scale ranges from 0 to 14 with 0 being the most acidic, 7 being neutral and 14 being the most alkaline. It is possible to raise or lower your pH levels with water changes or chemicals (use extreme caution!).

Magnesium -

Magnesium's primary importance is its interaction with the calcium and alkalinity balance in reef aquaria. Seawater and reef aquarium water are always supersaturated with calcium carbonate. That is, the solution's calcium and carbonate levels exceed the amount that the water can hold at equilibrium. How can that be? Magnesium is a big part of the answer. Whenever calcium carbonate begins to precipitate, magnesium binds to the growing surface of the calcium carbonate crystals. The magnesium effectively clogs the crystals' surface so that they no longer look like calcium carbonate, making them unable to attract more calcium and carbonate, so the precipitation stops. Without the magnesium, the abiotic (non-biological) precipitation of calcium carbonate would likely increase enough to prohibit the maintenance of calcium and alkalinity at natural levels.

Molybdenum -

Molybdenum plays a vital role in the biology of many marine invertebrates, filter bacteria, and seaweed. Among other functions, it is an essential component of certain enzymes produced by the above-mentioned organisms. Regular dosing of this element is vital for the long-term health of the reef aquarium ecosystem. Molybdenum is one of the elements constantly extracted from seawater and should therefore be added regularly.

Nitrates -

What to do if you have high nitrates??? First and foremost, understanding what nitrates are, their sources, alleviation and relative placement in a/the grand scheme of "water quality" is absolutely necessary for aquarists. In reality, nitrates by themselves are not "that" deleterious. What accumulating nitrogenous wastes in the form of nitrate compounds indicates may be symptomatic however, and signal a need to react (slowly) in changing ones management/maintenance of captive marine systems.

Nitrite -

Most aquarists have some familiarity with nitrite. It is part of the "nitrogen cycle" that takes place in aquariums, and so is one of the first encounters that many aquarists have with their aquaria chemistry. The marine aquarium hobby is replete with commentary about nitrite, some of which is unfortunately, incorrect or misleading. Its toxicity in marine systems is far lower than in freshwater systems. Nevertheless, many aquarists incorrectly extrapolate this toxicity to reef aquariums which suggest that any measurable amount of nitrite is a concern.

Phosphate -

The phosphorus atom is one of living matter's basic building blocks. It is present in every living creature and in every reef aquarium's water. Unfortunately, it is often present in excess in reef aquaria, and that excess has the potential to cause at least two substantial problems for reef keepers. The first is that phosphate is often a limiting nutrient for algae growth, so when elevated it can permit excessive growth of undesirable algae. The second is that it can directly inhibit calcification by corals and coralline algae. Because most reef keepers don't want either of these things to happen, they strive to keep phosphorus levels under control. Fortunately, there are several effective ways to keep phosphorus concentrations at acceptable levels.


- In natural seawater, potassium is a non-conservative major element with a concentration slightly lower than that of calcium. It is a component of aragonite, and regular dosing has, within the past several years, has been implicated in improving the blue coloration of numerous varieties of small-polyp stony corals; the benefits of potassium supplementation are potentially two-fold, then: provision of an element that is: 1) Incorporated into the skeletal material of corals and other reef-building organisms for purposes of growth, and 2) Incorporated into pigments that enhance blue coloration of small-polyp stony corals. The importance of potassium to marine organisms is most apparent when beginning to dose it in aquaria with depleted potassium concentrations and/or in which the sea salt mixture used is potassium-deficient; in such cases, changes in the appearance of many corals may be observed within the first weeks of regular dosing.

Silica -

Silica raises two issues. If diatoms are a problem in an established reef aquarium, they may indicate a substantial source of soluble silica, especially tap water. In that case, purifying the tap water will likely solve the problem. If diatoms are not a problem, aquarists should consider dosing soluble silica. Why dosing silica? Largely because creatures in our aquaria use it, the concentrations in many aquaria are below natural levels, and consequently the sponges, mollusks, and diatoms living in these aquaria may not be getting enough silica to thrive.

Strontium -

Scientific evidence indicates that some organisms need strontium. Certain gastropods, cephalopods, and radiolaria, for example, require strontium. Finally, anecdotal evidence from a number of advanced aquarists suggests that strontium that is substantially below natural levels is detrimental to the growth of corals that many aquarists maintain.


Don't take the quality of your tap water for granted. If you are using tap water from municipal department, the water may look crystal clear, but it may still contain levels of substances toxic that are not harmful to you, but it is to your fish.

Most municipalities add chlorine or chloramines to the water. Both are detrimental to the gills of your fish. It may also contain phosphate to protect their pipes, although these are not toxic, they can energise aggressive algae growth in your aquarium. Potentially harmful heavy metals are likely to be present. Iron, for example, is commonly found in tap water, and can also come from galvanised pipes from plumbing. Though not usually found in high enough concentrations to be toxic, it too can energise algae.

Copper can also come from copper plumbing. Most fish can tolerate copper in low levels for a short time, but it can be particularly devastating to any aquarium containing invertebrates. Once copper has been introduced in a reef aquarium, extreme measures may be needed to re-create a suitable environment.

If you have, galvanised, or copper pipes, it is always a good idea to allow the water to run before using it in your aquarium. This will help rinse out any loose molecules that have built up in the pipes. However, If you choose to keep copper-sensitive fish, invertebrates, or a reef aquarium, a copper test kit, is a must have. It is an inexpensive way to help head off serious problems “prevention is better than cure”.

Though the municipal water will vary from day to day, some water conditioners can detoxify heavy metals, allowing them to precipitate so they can be removed by your filtration. But if your tap water test indicates the presence of high levels of copper, then you might want to consider purifying the water with the addition of a Reverse Osmosis unit (RO) to maintain healthy water conditions in your aquarium.

Testing your tap water regularly for heavy metals will help you maintain these minerals and their by-products at safe levels.