Pond Management

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Pond Management

• pH, Alkalinity Liming

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pH

• Indicates whether water is acid, base or
  neutral
• Rapid or large changes can stress or kill
  aquatic animals
• A range of 6.5 to 9.0 is desirable

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Desired range for aquaculture
Death
Death
4.0
9.0
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6.5
0
7
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pH
Fig. 2. pH scale showing recommended range
(Wurts Durborow, 1992). A pH of 7 is neutral,
pH lt 7 is acidic , pH gt 7 is basic (alkaline).
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Alkalinity

• Measures how much base is present in water
• Desired range for most species 50 to 150 ppm,
  but must be above 20 ppm (mg/L)
• Desired range prevents large changes in pH

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Early Morning
Early Morning
Late Afternoon
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Liming

• Adding ag. limestone will increase pH
  alkalinity
• Collect soil samples from pond bottom to a
  depth of 6 inches
• Send samples to university soil lab
• Use recommendation for Alfalfa

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Benefits of Liming

• Helps prevent wide swings in pH
• Enhances the effect of fertilization
• Adds calcium and magnesium to water

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Hardness

• Indirect measure of divalent salts in water
• Most common sources are Calcium Magnesium

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Ponds with Water

• Collect water sample
• Test for total alkalinity
• If total alkalinity is lt 20, pond should be limed
• Some swimming pool test kits measure alkalinity

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Pond Productivity

• Raising alkalinity increases nutrient
  availability phytoplankton
• Ag. lime and / or gypsum can clear muddy water
  which improves light penetration

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Fertilizing Ponds
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Aquatic Food Chain

• Phytoplankton
• Zooplankton
• Small Insects
• Small Fish (minnows bluegills)
• Large Fish (bass catfish)

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Inorganic Fertilizers

• Formulated with chemicals
• Nitrogen, Phosphorus, Potassium (NPK)
• Stimulate phytoplankton, then Zooplankton

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Adding Fertilizer

• Slowly dissolve 10 to 30 lb per acre of liquid or
  granular fertilizer into pond
• Add at 2-week intervals, no more than 3 times
• Use secchi disk to evaluate success
• Desired secchi disk measurement 18 to 24 inches

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On-Line Literature

• www.ca.uky.edu/wkrec/WurtsLitpage.htm

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Extension Aquaculture Specialist
Dr. Bill Wurts
Kentucky State University CEP