Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations fish kill

Hello sadworld:

It sounds as though you killed off too much plankton algae at one time. Even though you have an aeration system, it is desiged to circulate the low oxygen water to the surface, allow the hydrogen sulfide, carbon dioxide and amonia to off-gas and only then will the water molecule have any room to absorb an oxygen molecule.

The system was most likely doing fine but when you did your green clean and dye treatment, the oxygen dropped so low due to the die off of the algae that the aeration system could not meet the demand.

A good example is when you take out a loan to purchase a vehicle. You make enough money to pay the payment until you loose your job, (the treatment) now you can not make the payments and you loose the vehicle, (dead fish)

How to stop the die off? Emergency aeration. Some sort of surface aeration apparatus. Preferably prop driven. Be it a floating aeration system, paddal wheel, trash pump plulling top water and then blowing it over the surface of the water in a fan pattern or even your bass boat backed in still attached to the trailer with the motor trimmed up to produce some sort of surface spray all will aid in stopping any more fish from being lost. I have even had one client bring their local fire dept to test their pumps and spray the water from their deck guns to aerate the pond.

Testing:

Dissolved Oxygen: Dissolved oxygen is the most critical indicator of a lake’s health and water quality. Dissolved oxygen levels in natural waters are dependent on the physical, chemical and biochemical activities prevailing in the water body. Oxygen is added to aquatic diffusion at the water’s surface and atmosphere interface. Oxygen is depleted primarily by animal and plant respiration and decomposition. Oxygen is required for fast oxidation of o9rganic wastes including bottom muck. Anaerobic bacteria, including fecal coliforms are destroyed by high oxygen levels.

For a healthy game-fish population, oxygen levels in the 6-10 mg/l range are necessary. Respiration stress occurs when oxygen levels are reduced to 4-5 mg/l.

Hydrogen Sulfide: Sulfide is a poisonous by-product of the anaerobic decomposition of organic matter and is not common in surface waters. Dissolved hydrogen sulfide is one of the two forms of sulfide that can be present in a water body. This odorous and poisonous gas is harmful to fish at levels higher than 0.4 mg/l.

The toxicity of hydrogen sulfide is equivalent to that of hydrogen cyanide, but its offensive odor is detectable long before toxic levels are reached. Normally, this gas should only be smelled by stirring bottom muck. Normal dissolved oxygen levels destroy the anaerobic bacteria which produce hydrogen sulfide.

Nitrogen and Ammonia: These gases are products of the microbiological decay of plant and animal matter and fertilizer runoff. When available, these nutrients contribute to plant and algae growth. Concentrations below 0.3 mg/l significantly limit plant and algae populations. Reduced fertilizer applications near shorelines will help prevent increase in these and other nutrient levels.

Chlorides: The chloride ion is one of the major inorganic anions in water and wastewater. In coastal communities, chloride levels may be high due to saltwater intrusion. Surface waters containing 250 mg/l sodium chloride will have a detectable salty taste.

Conductivity: Conductivity is determined by the total concentration of the ionized substances dissolved in the water. The concentration of these dissolved substances is measured by the water sample’s ability to carry an electrical current. A significant increase in conductivity may indicate a recent increase in domestic or industrial pollution.

Color: Color in water is a result of natural iron and maganese ions, decomposing organic plant material, tannin, plankton algae and industrial and domestic pollution. Changes in color may reflect increases in dissolved nutrient levels.

Turbidity: Turbidity in natural waters is caused by the presence of suspended solids such as silt, clay, fine organic and inorganic matter, plankton and other microscopic organisms. The turbidity test measures an optical property of the water sample and is used as an index of water clarity. Turbidity values of 60 N.T. U.’s (Nephelomtric Turbidity Units) or more indicate high sediment concentrations, usually due to construction activity in the drainage basin.

pHs: The pH value of a water body expresses its tendency to donate or accept hydrogen ions on a scale of 0 (very acidic) to 14 (very basic). Natural waters range from pH6 to pH9 and are often slightly basic. Any major pH deviations for a given water body indicate the intrusion of strongly acidic or basic industrial wastes.

For a lab: I know of one that is found through out North America and that is Test America.

I hope you are able to stop your fish kill soon.