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Testing The Pond pH Level
If your pond doesn't have just the right pH level, fish are in trouble. pH is the measure of alkalinity or acidity. When the pH of the water is balanced, aquatic life and plants thrive.
Andy Goodwin with the U.S. Fish and Wildlife Service says problems become noticeable when the water is too acidic.
"Ponds that are acidy, tend to be either muddy or clear. They don't ever look that nice healthy green color. Some of them look like tea. And the fish will grow fairly slowly because the food chain is not working very well," says Goodwin. "The other thing you'll see is fish die sometimes late in the winter or early in the spring, especially during periods of rainy weather. It'll be assorted sizes and species of fish, and just a few each day."
You'll need to have the water tested. Take samples from various locations of the pond, several inches below the surface, and as far away from the bank as possible. Mix them all together, and pour about a pint of the water into a clean, plastic container. The extension office can do the testing for you, or tell you where it can be done.
Nathan Stone is a fish specialist at the University of Arkansas. He says most fish do best within a pH range of 6.5 to 9.5
"If the alkalinity is below 20-milligrams-per-liter, then it would be worth getting the bottom soil of the pond checked through the extension office, and then that would give a liming recommendation for the tons of ag lime that could be used to bring up the bottom pH and to help increase the alkalinity and hardness of the water," says Stone.
When a pond is prone to low pH levels, the water should be tested annually. The colder months are an ideal time to add agricultural limestone. It may take anywhere from a few days to as much as a month to alter the water chemistry.