SL10603-water management

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SL10603 : 

SL10603 Water Management 1

Water quality and fish health : 

Water quality and fish health The single, most important factor affecting fish health and influencing disease in fish ponds and tanks is water quality. Raised levels of ammonia or nitrite, sub-optimum pH and water hardness levels or a high level of organic pollution will be stressful to fish; predisposing them to disease. If we are to create healthy, optimum conditions and prevent disease, it is important to be clear what is actually meant by good water quality. 2

1. Low ammonia and nitrite : 

1. Low ammonia and nitrite Fish are constantly polluting their own environment and producing ammonia. Both ammonia and nitrite are highly dangerous, causing stress and physical damage to sensitive tissues. A major, major requirement of any fish keeping system is no detectable levels of either. This particularly applies to new set-ups (new pond syndrome) and heavily stocked koi ponds. Biological filtration may be needed to maintain optimum levels. 3

2. Chemically clean water : 

2. Chemically clean water The water should be chemically clean and free of chemicals such as pesticides, chlorine, heavy metals, organophosphates and chemicals used to treat fish diseases. The presence of any toxic chemicals, even at fairly low levels, may be harmful. 4

3. Water hardness, pH and temperature : 

3. Water hardness, pH and temperature Different species of fish have specific requirements for essential water parameters such as pH, water hardness, alkalinity and temperature. Conditions outside of what are fairly narrow limits are liable to create stress.  Water that fails to meet these criteria cannot for obvious reasons be considered good water quality 5

4. Low levels of organic pollution : 

4. Low levels of organic pollution In addition to fish waste, the pond or tank is also being continuously polluted with uneaten food, algae and other detritus. As this organic matter decomposes it produces many organic and inorganic compounds. Biological filtration will take care of ammonia and nitrite, but there may be a build up of dissolved and particulate organic compounds. High levels of organics can create conditions that encourage disease, parasites and opportunistic bacteria. Water with high levels of organic matter cannot be considered good water quality. 6

5. Stability not fluctuation : 

5. Stability not fluctuation Depending on the water chemistry, stocking levels and pond design, it is possible to have substantial fluctuations of pH, temperature and other parameters over a 24-hour period. Constant changes - even if they stay within the preferred range are liable to be extremely stressful, as the fish have to constantly adapt to changing conditions. An example might be pH that varies between, 7 in the morning, rising to 9-10 in the evening on a hot sunny day. 7

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Apart from stressing the fish, it will have other implications for other water chemistry aspects such as ammonia and many common disease treatments. Water that constantly fluctuates in quality and conditions cannot be said to be good water quality 8

Water Quality : 

Water Quality When  a hatchery is on a reuse system, it is necessary to monitor many parameters  to insure the water quality is optimum for fish survival 9

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Why Temperature Is Important Human activities should not change water temperatures beyond natural seasonal fluctuations. To do so could disrupt aquatic ecosystems. Good temperatures are dependent on the type of stream you are monitoring. Lowland streams, known as "warmwater" streams, are different from mountian or spring fed streams that are normally cool. 11

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In a warmwater stream temperatures should not exceed 89 degrees (Fahrenheit). Cold water streams should not exceed 68 degrees (Fahrenheit). Often summer head can cause fish kills in ponds because high temperatures reduce available oxygen in the water. 12

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Why pH Is Important pH is a measure of the acidic or basic (alkaline) nature of a solution. The concentration of the hydrogen ion [H+] activity in a solution determines the pH. 13

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Environmental Impact: A pH range of 6.0 to 9.0 appears to provide protection for the life of freshwater fish and bottom dwelling invertebrates Runoff from agricultural, domestic, and industrial areas may contain iron, aluminum, ammonia, mercury or other elements. The pH of the water will determine the toxic effects, if any, of these substances. For example, 4 mg/l of iron would not present a toxic effect at a pH of 4.8. However, as little as 0.9 mg/l of iron at a pH of 5.5 can cause fish to die. 14

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Min. Max. Effects 3.8 10.0 Fish eggs could be hatched, but deformed young are often produced 4.0 10.1 Limits for the most resistant fish species 4.1 9.5 Range tolerated by trout --- 4.3 Carp die in five days 4.5 9.0 Trout eggs and larvae develop normally 4.6 9.5 Limits for perch --- 5.0 Limits for stickleback fish 5.0 9.0 Tolerable range for most fish --- 8.7 Upper limit for good fishing waters 5.4 11.4 Fish avoid waters beyond these limits 6.0 7.2 Optimum (best) range for fish eggs --- 1.0 Mosquito larvae are destroyed at this pH value 3.3 4.7 Mosquito larvae live within this range 7.5 8.4 Best range for the growth of algae 15

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Why Chlorides Are Important Chloride is a salt compound resulting from the combination of the gas chlorine and a metal. Some common chlorides include sodium chloride (NaCl) and magnesium chloride (MgCl2). Chlorine alone as Cl2 is highly toxic, and it is often used as a disinfectant. In combination with a metal such as sodium it becomes essential for life. Small amounts of chlorides are required for normal cell functions in plant and animal life. 16

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Environmental Impact: Chlorides are not usually harmful to people; however, the sodium part of table salt has been linked to heart and kidney disease. Sodium chloride may impart a salty taste at 250 mg/l; however, calcium or magnesium chloride are not usually detected by taste until levels of 1000 mg/l are reached. Public drinking water standards require chloride levels not to exceed 250 mg/l. 17

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Chlorides can corrode metals and affect the taste of food products. Therefore, water that is used in industry or processed for any use has a recommended maximum chloride level. Chlorides can contaminate freshwater streams and lakes. Fish and aquatic communities cannot survive in high levels of chlorides 18

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Why Dissolved Oxygen is Important Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis. When performing the dissolved oxygen test, only grab samples should be used, and the analysis should be performed immediately. Therefore, this is a field test that should be performed on site. 19

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Environmental Impact: Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from "gas bubble disease"; however, this is a very rare occurrence. 20

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The bubbles or emboli block the flow of blood through blood vessels causing death. External bubbles (emphysema) can also occur and be seen on fins, on skin and on other tissue. Aquatic invertebrates are also affected by gas bubble disease but at levels higher than those lethal to fish. 22

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Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. 23

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Why Total Iron Is Important Iron is the fourth most abundant element, by weight, in the earth's crust. Natural waters contain variable amounts of iron despite its universal distribution and abundance. Iron in groundwater is normally present in the ferrous or bivalent form [Fe++] which is a soluble state. 24

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It is easily oxidized to ferric iron [Fe+++] or insoluble iron upon exposure to air. Iron is a trace element required by both plants and animals. It is a vital oxygen transport mechanism in the blood of all vertebrate and some invertebrate animals. 25

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Environmental Impact: Iron in water may be present in varying quantities depending upon the geological area and other chemical components of the waterway. Ferrous Fe++ and ferric Fe+++ ions are the primary forms of concern in the aquatic environment. The ferrous form Fe++ can persist in water void of dissolved oxygen and usually originates from groundwater or mines that are pumped or drained. 26

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Iron in domestic water supply systems stains laundry and porcelain. It appears to be more of a nuisance than a potential health hazard. Taste thresholds of iron in water are 0.1 mg/l for ferrous iron and 0.2 mg/l ferric iron, giving a bitter or an astringent taste. Black or brown swamp waters may contain iron concentrations of several mg/l in the presence or absence of dissolved oxygen, but this iron form has little effect on aquatic life. 27

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Why Nitrate, Nitrite, and Nitrogen Are Important Nitrogen is one of the most abundant elements. About 80 percent of the air we breath is nitrogen. It is found in the cells of all living things and is a major component of proteins. Inorganic nitrogen may exist in the free state as a gas N2, or as nitrate NO3-, nitrite NO2-, or ammonia NH3+. Organic nitrogen is found in proteins and is continually recycled by plants and animals. 28

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Environmental Impact: Nitrogen-containing compounds act as nutrients in streams and rivers. Nitrate reactions [NO3-] in fresh water can cause oxygen depletion. Thus, aquatic organisms depending on the supply of oxygen in the stream will die. 30

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The major routes of entry of nitrogen into bodies of water are municipal and industrial wastewater, septic tanks, feed lot discharges, animal wastes (including birds and fish) and discharges from car exhausts. Bacteria in water quickly convert nitrites [NO2-] to nitrates [NO3-]. Nitrites can produce a serious condition in fish called "brown blood disease." Nitrites also react directly with hemoglobin in human blood and other warm-blooded animals to produce methemoglobin. 31

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Methemoglobin destroys the ability of red blood cells to transport oxygen. This condition is especially serious in babies under three months of age. It causes a condition known as methemoglobinemia or "blue baby" disease. Water with nitrite levels exceeding 1.0 mg/l should not be used for feeding babies. Nitrite/nitrogen levels below 90 mg/l and nitrate levels below 0.5 mg/l seem to have no effect on warm water fish. 32

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Why Phosphorus Is Important Phosphorus is one of the key elements necessary for growth of plants and animals. Phosphorus in elemental form is very toxic and is subject to bioaccumulation. Phosphates PO4--- are formed from this element. Phosphates exist in three forms: orthophosphate, metaphosphate (or polyphosphate) and organically bound phosphate. Each compound contains phosphorous in a different chemical formula. 33

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Ortho forms are produced by natural processes and are found in sewage. Poly forms are used for treating boiler waters and in detergents. In water, they change into the ortho form. Organic phosphates are important in nature. Their occurrence may result from the breakdown of organic pesticides which contain phosphates. They may exist in solution, as particles, loose fragments, or in the bodies of aquatic organisms. 34

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Environmental Impact: Rainfall can cause varying amounts of phosphates to wash from farm soils into nearby waterways. Phosphate will stimulate the growth of plankton and aquatic plants which provide food for fish. This increased growth may cause an increase in the fish population and improve the overall water quality. However, if an excess of phosphate enters the waterway, algae and aquatic plants will grow wildly, choke up the waterway and use up large amounts of oxygen. 36

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This condition is known as eutrophication or over-fertilization of receiving waters. The rapid growth of aquatic vegetation can cause the death and decay of vegetation and aquatic life because of the decrease in dissolved oxygen levels. Phosphates are not toxic to people or animals unless they are present in very high levels. Digestive problems could occur from extremely high levels of phosphate. 37

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Why Fecal Coliform Testing Is Important Total coliform bacteria are a collection of relatively harmless microorganisms that live in large numbers in the intestines of man and warm- and cold-blooded animals. They aid in the digestion of food. A specific subgroup of this collection is the fecal coliform bacteria, the most common member being Escherichia coli. These organisms may be separated from the total coliform group by their ability to grow at elevated temperatures and are associated only with the fecal material of warm-blooded animals. 39

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Environmental Impact: The presence of fecal coliform bacteria in aquatic environments indicates that the water has been contaminated with the fecal material of man or other animals. At the time this occurred, the source water may have been contaminated by pathogens or disease producing bacteria or viruses which can also exist in fecal material. Some waterborne pathogenic diseases include typhoid fever, viral and bacterial gastroenteritis and hepatitis A. 40

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The presence of fecal contamination is an indicator that a potential health risk exists for individuals exposed to this water. Fecal coliform bacteria may occur in ambient water as a result of the overflow of domestic sewage or nonpoint sources of human and animal waste. 41

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