Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Water terminology

  • Aerobic, water where biological processes occur that requires oxygen
  • Alkalinity, Alk, mostly used for marines is the term used for the compounds in the water that offset the changes in pH due to the acidic substances. This often measures carbonates and bicarbonates.
  • Ammonia, NH3, A toxic substance that is excreted by the fish and bacteria when they break down organic waste in the aquarium.
  • Anaerobic, water where biological processes occur in the absence of oxygen
  • Carbon Dioxide, CO2, A gas sometimes added to tanks to encourage plant growth.
  • Carbonic Acid When Carbon Dioxide dissolves in water it forms Carbonic Acid. CO2 + H2O = H2CO3.
  • Chloramines, a compound made using chlorine gas and liquid ammonia used in the same way as chlorine. While it is more stable than chlorine and odorless, it is not quite as effective so more of the compound needs to be added to drinking water supplies. However it can still be detrimental to aquatic systems.
  • Chlorine, often found in tap water and is used to kill micro-organisms that can be harmful to humans, but can be detrimental to aquatic systems.
  • Dechlorinated, Usually Sodium thiosulphate, It is used to remove the Chlorine from tap water. When used with chloramines it will break the bond between the chlorine and ammonia leave a trace amount of ammonia in the water.
  • GH, refers to the overall hardness of the water, or the amount of dissolved minerals (usually Calcium and Magnesium).
  • Hydrogen Sulphide, A very toxic and smelly gas, that is formed in anaerobic conditions, i.e. when the gravel is to deep and contains a lot of waste. A classic sign for it is a bad egg smell and in more serious cases the gravel will turn black.
  • Inert, Any material that will not alter the water chemistry in any way.
  • Kalkwasser, a trade name for calcium hydroxide commonly used to boost the pH and calcium levels in a marine tank
  • KH, refers to the amount of Calcium Bicarbonate (CaHCO3) is present in the water. This is also called temporary hardness because it is removed by boiling. Also it is referred to as the waters buffering capacity.
  • Nitrite, NO2, This is what the Ammonia is changed into when it is Oxidized by bacteria. It is still very toxic to fish at this stage.
  • Nitrate, NO3, This what the Nitrite is changed into by another type of bacteria, it is relatively harmless in low levels. And by changing some of the water on a regular basis (every two weeks) the levels of Nitrate will be kept quite low.
  • Oxidation Reduction Potential, ORP, the tendency for compounds to lose or gain electrons thereby changing the chemical forms.
  • Ozone, Is an unusual form of Oxygen (O3 rather than (O2). It is a powerful sterilizing agent and is used in Marine fish keeping to greatly increase the efficiency of Protein Skimmers.
  • pH refers to how acidic or alkaline the water is it is measure on a scale from 0 to 14, 0 is very acidic, 14 is very alkaline, 7 is neutral. Most freshwater fish live between 6.5 to 7.5, Salt water fish live between 8.2 to 8.4.
  • Phosphate, PO4, This can come in to the water from a variety of sources (even from filter Carbon). It is responsible for causing Algae to run rampant in the tank. But in very very low levels it can be a problem, parts per 10,000,000 (ten million) basically if it can be detected there is to much. There are some special filter media that can remove it and if you are suffering from a persistent algae problem even though you seem to be doing everything else right, try one of the Phosphate removing filter media.
  • Particulate Organic Matter, POM, organic material that is present in the water column that are larger than 0.4um. Low levels are desirable to ensure maximum light penetration through the water.
  • Salinity, the amount of salts disolved in water. Marine water has around 34ppm
  • Specific Gravity, SG, the density of water and all it's dissolved compounds. This is a temperature dependent measurement so in order to determine the salinity of water a temperature corrected chart must be used. Pure distilled water has a SG of 1.000 while Reef tanks are generally between 1.024 - 1.028 at 25C
  • T.D.S, Total dissolved solids.
  • Trace element, Chemicals in very small amounts (microgram's or milligram's) found in the water, these sometimes play a vital role in fish and plant health