Water Quality

In order to provide your fish with the optimum setting, you must first understand the aquatic factors which affect them.  These conditions are a part of the aquarium environment you provide, and determine if your fish will thrive of if they will merely survive.

The water parameters affecting your fish may be divided into two categories: physical and chemical.  The physical environment includes aquarium size, water temperature, and length of day.  Chemical factors include chlorine and chloramine, general and carbonate hardness, pH, oxygen and carbon dioxide levels, phosphate levels, and nitrogenous waste levels.  Nitrogenous waste may be further divided into ammonia (NH4), nitrite (NO2), and nitrate (NO3).

All of these factors interact to determine the specific quality of your water.   However, the physical factors of the environment are less interrelated that are the chemical characteristics.

The physical conditions in your aquarium are by far the easier to manipulate.  The water temperature should by in the mid to upper 70s for most fish.  However, goldfish and game fish prefer water in the low 60s, while discuss and a few other species need temperatures in the upper 80s.  Temperature stability is crucial, very few species of fish will withstand rapid temperature fluctuation.  The aquarium should receive from 10 to 12 hours of light each day.

The chemical conditions in your aquarium are more complicated and occupy the remainder of this piece.

When discussing water quality the first thing to consider is your source water.   In A World Of Fish's customer base aquarists use city tap water, well water and a variety of other public water sources.  In the metropolitan area the tap water contains high levels of chloramines and heavy metals.  A high quality water conditioner, such as Amquel, is essential to making municipal water habitable. 

Among the first water parameters you will need to think about is pH.  This is the ratio of hydrogen ions to hydroxyl ions in the water.  In lay terms, it is a measure of how acid or base the water is.  A pH below 7 is acid and above 7 is alkaline.   The pH requirements of different fish vary considerably.  Depending on the species, freshwater fish do best at a pH between 6.0 and 8.0.  Ask your A World Of Fish representative, or consult one of our many reference books if you have questions about a specific species.  Marine fish should generally be kept at a pH of 8.3.   Marine invertebrates do better with a pH of 8.4 or 8.5.

Water hardness is intimately related to pH.  General hardness (GH) is the total amount of dissolved solids in the water. Carbonate hardness (KH) is the measure of dissolved carbon components.  KH is a major factor in maintaining a stable pH.   If the KH is too low, the pH can plummet to unsafe levels.  At a pH below 5, the nitrogen cycle is disrupted, which can lead to toxic levels of ammonia.

Most aquarium test kits measure hardness in German degrees hardness, or dH.  KH is more important to the aquarist than is GH.  As a general rule, fish that prefer a lower pH also do better in water with a low KH.  Most tropical freshwater community fish do best with a KH of 3-6dH.  Saltwater fish prefer a KH of about 9dH.   Marine reef tanks should have a KH of 14dH or slightly above. 

The amounts of dissolved oxygen (O2) and carbon dioxide (CO2) are also vital to your fish's health.  As your fish breathe, they use )2 and give off CO2.  To remove the CO2 and replenish the O2, surface turbulence is required.  This turbulence may be from an air pump, a power head directed towards the water surface, or water falling through a wet/dry filter.

There are two main consumers of oxygen in the aquarium.  The fish are the most obvious.  However, there is something in your aquarium that uses more O2 than your fish: the biological filter.  The bacteria in the filter consume far more O2 than the fish.

The physical characteristics of your aquarium also affect the amount of O2 and CO2 in the water.  As water temperature increases, its O2 capacity decreases.  The amount of surface area is also a limiting factor in the exchange of O2 and CO2.   Thus, rectangular aquariums, with their greater surface area, can house more fish than can hexagonal and pentagonal aquariums of the same volume. 

Phosphates can also play an important role in certain types of aquariums.  They are primarily a concern for marine reef tanks and freshwater plant aquariums.  Some phosphates can enter the aquarium through tap water, but the largest source is fish food.   In reef tanks, phosphates can harm corals and anemones.  In plant tanks they can affect plant growth and health.  In all aquariums, excessive levels of phosphates can lead to algae blooms.

The final, and most important, chemical parameters to consider are the nitrogenous wastes.  Fish excrete ammonia into the water.  The ammonia is transformed into nitrite, which is then turned into nitrate.  Each of these chemicals can be toxic to fish.  The process is called nitrification, and is more fully discussed in the AquaNote entitled Nitrogen Cycle.

We have summarized the major factors which affect water quality in the aquarium.   Your fish live in this water.  This makes the water quality of the utmost importance to their health and well-being.  Unfortunately, the aquarium industry has yet to develop a maintenance free aquarium.  Regular water changes are a vital tool to help you maintain the quality of your water.  Nitrates and phosphates build up over time, while hardness and pH tend to drop.  Performing water changes on a regular basis helps ensure that these factors remain stable. 

Having easy-to-use aquarium test kits at home makes it possible to test your aquarium and source water before water changes.  This will allow you to adjust the water chemistry, if necessary, to meet the optimum conditions needed by your fish.

When trying to help an aquarist diagnose trouble in the aquarium, we at A World Of Fish always request a water sample and test ammonia, nitrites, and pH.  Other tests may be run if the situation warrants.

Your A World Of Fish representative will use the results of these tests and other information provided by the aquarist to determine a course of action.  Sometimes, it is necessary to replace or upgrade a filter, heater, or pump.  Other times, a buffer or water additive may be needed to improve water quality.  Frequently, we simply recommend waiting and watching.  Given time, many issues will resolve themselves.

There are few things more enjoyable and more relaxing than a well maintained aquarium, where the inhabitants are not only surviving, but thriving.  For this to occur, high water quality is a must.