Water is not the same the world over. Whilst we attempt to keep 'community collections' of fish in one type of water we should also appreciate that not all fish require the same water conditions as these may vary from locality to locality.

WATER QUALITIES : These are usually centred around a few major
                                    component values, although it is possible to test
                                    water for the most minor components if so desired.

Those of most importance (or concern!) to aquarists are the following:

pH: Degree of acidity or alkalinity.
      Measured from 0pH (extreme acid) to 14pH (extreme alkaline)
      Tapwater - 7.2 - 8 (hard water areas) and 7 (soft water areas)
      Rainwater - generally 7 or below (depending on prevailing air pollution)
      Saltwater (natural seawater or synthetic mixed) 8.3

HARDNESS (oDH): 0 - 3o (soft) 8-10o (medium hard) 16o plus (very hard)
Often hardness is expressed as 'parts per million' (ppm).

0 - 75 ppm is approx 0 to 4 deg DH
75 - 150 ppm is approx 4 - 8 deg DH
150 - 300 ppm is 8 to 16 deg DH
300 plus is More than 16 deg DH.

See Acclimatising 'soft water' fish to hard water

SPECIFIC GRAVITY (marines only): This is a comparison of density between                                  sea water and pure water.
Some public aquariums run at lower than normal 1.024 value so as to control parasitic attacks. Usual marine aquarium range - 1.020 - 1.024 at 24oC.

AMMONIA and NITRITE: These compounds are toxic to fish and are         
                                         formed as a result of decaying or decomposing
materials (faecal waste, uneaten food, dead plants etc) and are responsible for 'New Tank Syndrome' fish losses.
Can be reduced by nitrifying bacteria in biological filters. Once biological filter has matured, readings should be 'zero'.

NITRATE: Less toxic to fish and often utilised by plants as food.
                 Test readings will gradually rise due to production by nitrifying
                 bacteria. Keep in check by regular partial water changes.

PHOSPHATE: Another 'ingredient' of tapwater which, with nitrate,
                     encourages algae growth. Can be removed with RowaPhos(tm)

CHLORINE/CHLORAMINE: Added to the domestic water supplies to                                             safeguard human health ? not fishes'!
Chlorine is usually dissipated by vigorous aeration or even simply the process of filling the tank. Chloramine is best reduced or eradicated by means of proprietary additives.

R O Water: Of specific interest to marine fishkeepers, R O Water
                   is water that has been passed through a Reverse Osmosis unit to
                   remove all heavy metals and contaminants before being used to
                   mix with synthetic sea salt.

                   Similar to distilled water, R O Water is 'lifeless' although when
                   purchased from an aquatic dealer the option is usually offered
                   to add some trace elements at the point of sale.
                   In freshwater aquariums it is usual to mix some ordinary water
                   with R O Water.

WATER CARE Attention to water quality is the secret of success in
                       fishkeeping. Good water management can only be obtained by
                       using filtration coupled with regular partial water changes.

Do not subject your fish to any sudden change in water quality or temperature: this will induce stress which, in turn may affect the fish's immune system and so render it open to attack from disease.

It is vital that when moving fish to another location (moving house or even to Fish Shows) you take as much of their normal aquarium water with you so as to make the transfer as stress-free as possible.

See Transporting & Exhibiting Fish, Aquarium Management Care Sheet No: 9

Remember that anything (and everything) that is put into the aquarium will affect the water condition to some degree.

Keep soluble rocks and those containing metallic ores out of the aquarium; similarly, innocent-looking aquarium ornaments can also have an effect on the water condition.

When mixing salt water for marine fishes, use 'food quality' plastic containers ? and make sure their use is conscientiously restricted for aquarium purposes.

© FBAS 1998 RCM/RDE            Aquarium Management Care Sheet 2 1/1

                                       Download this Care Sheet