Aquarium Water Quality

Successful fishkeeping depends largely on maintaining good water quality. The most important components are as follows:

pH
Temperature
Water hardness
Dissolved oxygen
Chlorine
Nitrogen compounds

pH

pH is a measure of acidity or alkalinity. The pH scale is from 1 to 14, 1 being very acid, 7 neutral and 14 very alkaline. Most community tropical fish can be maintained at a pH of 7. Goldfish prefer slightly alkaline water at 7.5. pH may be monitored with a test kit. For small to medium aquariums Proper pH tablets are an ideal way of achieving the correct pH as they are contain a buffer which will keep the pH stable through several partial water changes. For larger aquariums a liquid additive is available, which should be used in conjunction with a test kit. Adjust the pH gradually, no more than .2 every four hours to avoid ‘pH shock’.

WATER HARDNESS

Water hardness is a measure of the amount of dissolved mineral salts in the water. Expressed in °dH, each degree is equivalent to 30mg of calcium per litre of water. Most fish prefer medium hard to hard water, 9 - 19 °dH. Test kits are available to monitor this

CHLORINE

Chlorine is an additive to tapwater and harms fish by damaging their protective ‘mucous’ coating. Either allow water to stand for 24 hours or use a chlorine removing product for immediate use.

TEMPERATURE

Most tropical fish can be maintained at 25°C (77°F). Goldfish and other coldwater fish do not require the addition of any heating. Avoid rapid or extreme temperature fluctuations, particularly where fish are kept indoors.

DISSOLVED OXYGEN

In a suitably stocked aquarium with adequate filtration, oxygen depletion should not pose a problem. Overfeeding however, will deplete oxygen levels through increased bacterial activity in the aquarium. Also, with rising temperature there is a corresponding decrease in oxygen levels.

An important point to remember is that oxygen only enters the water through the surface (other than that generated by plants), making surface water disturbance important. The movement of the water surface, which is usually generated by some form of filter, exposes more of the water body to the air, thereby maximising the uptake of oxygen.

NITROGEN COMPOUNDS AND THE NITROGEN CYCLE

AMMONIA AND NITRITE

Ammonia and nitrite are pollutants derived from waste from aquarium inhabitants, dead plants or fish and uneaten food. In an established aquarium, bacteria convert the ammonia and nitrite to a harmless form (nitrate). However, high levels of waste materials or uneaten food can overwhelm a filter system, particularly in a newly set up aquarium. Take care to remove any dead fish immediately, and that all food is consumed within a few minutes. Avoid overcrowding fish as this will also lead to dangerous levels of ammonia and nitrite.

To ensure water quality is maintained, install a good filter system and carry out regular partial water changes. Invest in good test kits and use them regularly - at least once per fortnight for established aquariums and more often for newly set up systems.