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WATER QUALITY Presentation on WATER QUALITY Introduction • What is water quality? • Why is water quality important when keeping fish in captivity? • Name three different types of water habitats that fish might live in. • What is the nitrogen cycle? • How do you know how ‘clean’ and ‘safe’ the water in a fish tank is? • What does pH stand for? Water Quality What is water quality? ANSWER • • • • Water (H20) is made up of 2 hydrogen and 1 oxygen atoms. Different elements contribute to the quality of water, depending on its source. The physical and chemical characteristics of water determine what kind of life it can support. These characteristics include things like: temperature, levels of toxic substances, level of dissolved oxygen, pH etc. Water Quality Why is water quality important when keeping fish in captivity? ANSWER • Inappropriate water quality can result in stress in captive species like fish. • Such stress can cause ill health, problems in fighting infection and accessing oxygen available in the water. Water Quality Environmental Adaptions • When keeping fish species in captivity it is important that the water quality best suited for the species is managed properly. • To do this you need to know what the species natural water habitat is. • The earth is a planet covered mainly by water and inhabited by a vast number of species all of which have evolved specialist physiological adaptions to survive the different water conditions that exist on the planet . Water Quality Water conditions • Earth although covered mostly by salt water, thanks to the planets water cycle provides water habitats that range from fresh water brackish water salt water of varying densities of salinity. Water Quality Temperature Zones Water temperature in captivity relates directly to the temperature zone of the planet that species inhabit in the wild. NB: • • Temperature varies with water depth and currents in the oceans. Temperature also varies in rivers & lakes at high altitude and such influences as melting ice caps. Water Quality Water Habitat Type Captive species can be categorised according to the type of water habitat and temperature they originate from. • • • • • Cold freshwater e.g. goldfish, stickleback, orf. Tropical freshwater e.g. gourami, neons, Coldwater marine e.g. blenni, Tropical marine e.g. yellow tang, seahorses, etc Brackish water or estuarine fish e.g. archer fish, monos Water Quality Freshwater • Rain water falls as fresh water (i.e. without salt) and joins streams that feed rivers and enter lakes. • During this process it erodes the surrounding land and dissolve rocks and minerals such as calcium and magnesium. • It is this dissolved mineral content that changes the levels of water hardness / softness Water Quality Marine • Marine refers to species living in a salt water environment. • Different species originate from regions with differing salt levels contained in the water. • Maintaining the correct salt levels in captivity is very important. • The amount of salt contained in the water is measured and monitored using a hydrometer. Water Quality Brackish Water • Where a river meets the sea the freshwater becomes mixed with sea water. E.g. mangrove swamps, estuaries. • Species that live in these areas have adapted to cope with these conditions and are able to tolerate a wide range of salt levels. Water Quality The Nitrogen Cycle • Fish produce waste that contaminates the water that they live in. • Dead and decaying organic waste produces poisonous ammonia ( NH3). Ammonia ( NH3) is also produced by the breakdown of proteins in the fish and is excreted through their gills. • The planet has a natural nitrogen cycle to help keep our waterways clean, the same cycle takes place within a fish tank. • The poisonous (NH3) ammonia is converted to the not quite so poisonous nitrite (NO2) by nitrosomonas bacteria • The poisonous nitrites (NO2) are converted to less harmful nitrates (NO3) by nitrobacter bacteria. To see the Nitrogen Cycle, view the animation in the water quality section. Water Quality Bacteria It is very important when maintaining an aquarium to ensure that the important bacteria: • • Nitrosomonas and Nitrobacter bacteria … are present in sufficient quantities to cope with the volume of waste produced by the fish population. If there is too small a bacteria population the levels of poisonous chemicals i.e. ammonia (NH3) and nitrites (NO2) will increase and kill the fish. Water Quality How do you know how ‘clean’ and ‘safe’ the water in a fish tank is? Regular monitoring of these levels can be carried out using water quality test kits. A number of different test kits are available and usually give colour indicators of the levels of such chemicals as: • • • • Ammonia Nitrites Nitrates pH To see how to use these kits view the videos in the water quality section. Water Quality What might be happening if the ammonia levels are above zero? ANSWER: • not enough nitrosomonas bacteria are present to convert the ammonia NH3 to nitrite NO2 Water Quality What might be the problem if the nitrite level is very high but the ammonia level is zero? ANSWER • There are enough nitrosomonas bacteria to convert the ammonia NH3 to nitrite NO2, but not enough nitrobactor bacteria to convert all the nitrite NO2 to Nitrate NO3. Water Quality Usually the test readings for an established tank are zero ammonia ( NH3), zero nitrites ( NO2) and a small reading of nitrates (NO3) What does this show us? ANSWER • This shows that the nitrogen cycle is working and that there are large enough populations of the right bacteria to convert the toxic ammonia (NH3) to Nitrites (NO2), and convert the Nitrites (NO2) to the less toxic Nitrates (NO3) Water Quality How do we reduce the level of the less toxic Nitrate(NO3) before it builds up to dangerous levels? ANSWER • • In order to help reduce the levels of the less toxic nitrate, routine fortnightly water changes of about 30% of the water should be carried out. Partial water changes may also be needed if the tests indicate very high levels of toxic chemicals NH3 & NO2. NB • Replacement tap water contains chorine which can strip the fish of their protective mucous membrane and kills the bacteria needed for the nitrogen cycle. • To prevent this a dechlorinator should be used or water that has been left to stand for 24 hours to allow the natural dissipation of chlorine. Water Quality Acid or Alkaline? The number of hydrogen ions present in the water determine if it is acid or alkaline. It is measured by the pondus hydrogenii (pH) scale. 0 1 2 most acid • • • 3 4 5 6 7 8 neutral 9 10 11 12 13 14 most alkaline Sudden changes in pH has a negative effect on fishes health. Different species have different tolerance levels of pH depending on their natural habitat. Higher pH increases the toxicity of ammonia.(NH3) Water Quality Materials that upset water quality • • • • • • • • • • Certain metals e.g. magnesium, copper, zinc Some rocks e.g. soluble rocks, calcareous rocks, rocks with metallic ore veins. Over feeding Over crowding of the fish population Decaying matter Poisons and pollutants drawn in from the atmosphere. Badly maintained filters Some pre – caste concrete decorations Some Coloured gravel pH Water Quality Do’s and Don’ts for Water Conditions • • • • • • Don’t make sudden changes to water conditions. When doing a regular change always use water of the correct composition and temperature. Don’t change fish from tank to tank unless the water conditions in each tank are exactly the same If rainwater is used as a source don’t collect it from a dirty roof or in metallic containers. Don’t let water anywhere near electrical equipment. Don’t use saltwater to top up evaporation in marine aquariums use freshwater instead, as salts aren’t lost during evaporation.