Introduction
Fish obtain their basic necessities from the water in which they live. The most characteristic feature of any aquarium system is therefore the quality of the water it contains. This water must be obtained from some source, pre-treated to make it suitable for the fish, delivered to the fish in sufficient quantities and maintained in good condition. Water quality is determined by physical, chemical and microbiological properties of water. These water quality characteristics throughout the world are characterized with wide variability. Therefore the quality of natural water sources used for different purposes should be established in terms of the specific water-quality parameters that most affect the possible use of water.
Temperature
The ideal temperature for a marine tropical fish aquarium is 78-82 degree Fahrenheit. The ideal temperature for a reef aquarium is 75-78 degrees Fahrenheit. Water quality issues are immediately addressed. If temperature is too high, reduce heater settings; if too low, increase heater settings or buy a heater that's rated for your tank size.
Nitrogen compounds that should be regularly checked in the aquarium include ammonia, nitrite, and nitrate.
Ammonia
Buildup of ammonia results from nitrifying bacteria breaking down aquarium waste. Ammonia (NH3) constantly converts to ammonium (NH4+), and vice versa, resulting in total ammonia (ammonia-N), which most test kits measure. Once the nitrogen cycle establishes in new aquariums, ammonia should never be detectable. Detecting ammonia, after cycling is complete, requires immediate action. Even low concentrations of ammonia-N severely stress fish. It makes them more vulnerable to disease and shortens their life span. If ammonia is left to accumulate in the aquarium it will be lethal.
Ammonia is highly toxic in freshwater aquariums. It’s even more toxic in reef and saltwater environments, due to a higher pH. The higher pH results in the presence of highly soluble ammonia gas, which is significantly more toxic.
Nitrite
The second stage of the nitrogen cycle produces nitrite. As soon as ammonia is available, nitrifying bacteria utilize the newly produced ammonia, enabling them to multiply and colonize inside the aquarium. Ammonia is predominantly converted into nitrite by the bacteria species Nitrosomonas. Once ammonia converts into nitrite, the bacteria species Nitrobacter converts the nitrite into nitrate. When a new aquarium is set up, the nitrogenous compounds will rise to high level, thereby starting the waste conversion process called the nitrogen cycle. Nitrosomonas and Nitrobacter are aerobic bacteria, requiring a constant flow of oxygen in order to survive and to perform their tasks.
Nitrite should never be detectable in an aquarium once the nitrogen cycle has been established. While nitrite is not as toxic as ammonia, it will cause significant fish stress at levels as low as 0.5ppm. Persistent nitrite levels exceeding 10-20 ppm will be lethal over time. If nitrite levels remain detectable for more than 7 days, take immediate action to bring relief to the aquarium’s inhabitants. Nitrite interferes with the oxygen metabolism of fish. Eventually it will destroy the fish’s hemoglobin (oxygen carrying cells)
Nitrate
Nitrate is the third and final stage of the nitrogen cycle. As outlined above, nitrifying bacteria convert aquarium waste into ammonia > nitrite > and finally nitrate. Unlike ammonia and nitrite, it is quite common to have some detectable levels of nitrate in an established aquarium. Nitrate is the main cause for algae growth and green aquarium water. Keeping nitrate low is the best preventive action a fish keeper can take to avoid ugly and messy algae outbreaks. Although less toxic than ammonia and nitrite, nitrate as a nitrogen compound still causes stress at all levels making a fish’s organs work harder to adjust to its new environment. The increased stress results in a lowering of ability to fight disease, healing capacity and reproduce. The lower the level, stress on the fish is less, as well as a much lower chance of algae (green water) outbreaks. The water exchange is the most common method of diluting nitrate in the aquarium. However, it may not be enough.
pH
pH is the measurement of hydrogen ions. Increased hydrogen ions leads to less bonding, resulting in a pH drop (more acidic water), while a decrease results in a pH rise (higher alkalinity).
pH = power of hydrogen
The lower the pH the water is more acidic, while a higher pH equals higher alkalinity. pH measures on a scale from 0 – 14. A pH of 7 is neutral. Changes in pH are a common cause of fish fatalities. Fish can adapt to various pH levels, provided it’s not too far out of the ideal range. Generally, a pH range from 6 – 8 is suitable for most species. However, fish cannot tolerate a constantly changing pH range. This is because pH is logarithmic (mathematical: meaning ten-fold). In other words, a change in pH from 7 to 6, results in water 10 times more acidic. An additional drop to a pH of 5, results in water 100 times more acidic than the neutral starting point of 7. If you have to adjust your aquarium’s pH, you must take carbonate hardness into consideration. The pH of harder water is more difficult to adjust because it bounces back, while soft water is more easily adjusted. The goal should always be to maintain a steady pH so adjustments can be avoided altogether.
Water Hardness (GH)
GH primarily measures calcium and magnesium ions. Water hardness is important for breeders. Some species require very soft water, which is hard to maintain. Successful breeding will require constant monitoring. The main significance is to choose fish suitable for existing water conditions.
Common measurements use ppm and the equivalent mg/l (To convert degrees into ppm, simply multiply by 17.8)
Carbonate Hardness (KH) or Alkalinity: KH measures dissolved bicarbonate and carbonate ions. They are commonly referred to as the buffering capacity.KH is very important because it determines stability of pH. When Carbonate ions bond with hydrogen ions forms pH. Increased bonding results in a higher pH, while fewer carbonate ions results in a lowered pH. A KH of 70 ppm and less will result the pH crash. Baking soda will increase KH, hence it will increase pH. Distilled water has a KH of 0 and therefore will lower the KH.
Phosphate
Phosphate originates within the aquarium. It is a by-product of the mineralization of waste materials, including those from plants, bacteria, fish excrement, uneaten food, fish slime, etc. Dead plant matter and rotting food particles settle on the substrate and within the filter. Rinsing filter materials and vacuuming the gravel during routine aquarium maintenance, significantly reduces phosphate accumulation by removing these internal sources. Phosphate enters the aquarium primarily by feeding the fish and can accumulate at an alarming rate. It is not toxic to fish, although even low levels can cause algae problems and have a detrimental effect on corals. To reduce it you should use a phosphate remover such as ‘Rowaphos’ in the aquarium & make sure all water changes and top ups are done using Reverse Osmosis water that is free of all impurities including phosphate and nitrate.
Less food = slower accumulation of phosphate
Chlorine / Chloramine
Water companies use Chlorine and Chloramine to disinfect tap water. Because both are harmful for fish, you should neutralize them prior to aquarium use. While chlorine airs out rather quickly in an aerated bucket, chloramine does not. Chloramine, a mixture of ammonia and chlorine, passes through the fish tissue directly into the bloodstream. Once entered in blood, it destroys oxygen carrying cells. Exposure to chloramine can kill all fish within 24 hours.
Salinity
Salinity is the measure of dissolved salt content in water. Salinity is typically measured in parts per thousand (ppt) or specific gravity (sg). The more salt in your water, the higher your readings will be. In saltwater aquarium salinity is usually kept between 1.020-1.028 sg. There are three common tools that aquarists used to test the salinity of their tanks.
They are as follows:
1. Hydrometer
Aquarium swing arm hydrometer used to test salinity of seawater. The cheapest way to measure salinity of a tank is Hydrometer.
A hydrometer tests for salinity is done by comparing the density of the water in an aquarium to the density of pure water (water without dissolved ions). If the tank contains plants, corals and critters like sea stars that are highly sensitive to changes in salinity, then the recommendation of skipping this option is done. A marine tank maintained at a temperature of 82 F (27.77 ̊ C) with a hydrometer reading of 1.021 translates into an actual specific gravity of 1.0237
2. Refractometer
Analog handled refractometer with eyepiece is used to measure aquarium water salinity. Refractometer is by far the most popular way to measure salinity among beginners and experts for their accurate results and affordability.
3. Salinity monitor
The one of the salinity measuring device is salinity monitor. This ranges from small pen testers and handheld units for occasional salinity tests to automated systems that continuously monitor the salinity and alert if it is above or below the preferred level. Salinity meter use a probe to test conductivity of the water. To put it simply, the probe records how the water reacts to electricity and uses this reading to determine the salinity of the water. A marine tank maintained at 80 F and a specific gravity reading of 1.0.22 has a salinity content of 31.8 ppt.
Calcium
It is a building block for corals, and for natural sea water has a level of 420ppm. The generally accepted optimum range for corals in aquariums is between 400 and 450ppm. Calcium can be depleted quickly in well stocked reef aquarium, but can easily be replenished and maintained by the frequent addition of a Calcium supplement e.g. Seachem Reef Complete.
Magnesium
Is the one of the most abundant elements in seawater, and is important for coral growth (especially soft corals) as well as for maintaining the pH. Its level can be maintained by frequent partial water exchanges using a high magnesium salt. Natural sea water contains 1285ppm of Magnesium, aim for around 1300ppm in aquariums.
Dissolved oxygen (O2 mg/L)
The amount of oxygen currently dissolved in a body of water. This gas is constantly entering the water from two main sources: The Atmosphere and from Photosynthesis. Dissolved oxygen concentrations can be determined by conducting a series of complex chemical reactions via a 'test kit' or by measuring electronically with an oxygen meter.
• A level of 7+ mg/ L is considered high
• A level of 5–6 mg/L is considered to be normal
• A level of 4 mg/L is considered low and getting potentially deadly
Inference
If there is abnormal condition exists in water quality that should be addressed immediately. The following parameters are major factors to be considered for a fish to be maintained healthy:
1. Temperature: If too high, reduce heater settings; if too low, increase heater settings or buy a heater that's rated for the tank size.
2. Salinity: If too high, replace some tank water with fresh water; if too low, add marine salt.
3. pH: There are many causes for incorrect pH; consult a fish care resource for specific strategies. Be sure to make any pH adjustments gradually — rapid changes can harm fish.
4. Ammonia: If any ammonia is detected and the levels are too high — check the filtration system for problems.
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