Clearing up muddy pond water

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It’s a common complaint, “My farm pond is muddy, and we’d like to enjoy clearer water. Do you have a solution?” Indeed, we do, but it may require habitat management or a bit of chemistry.

Muddy water is often a problem in Texas farm ponds because it inhibits the growth of natural fish food and is just not aesthetically pleasing. Additionally, the reduced visibility in ponds limits feeding of sight-feeding predators such as large mouth bass.

If heavy rainfall causes your pond to get muddy, but then clears up in a few days, you may simply need to alter the habitat surrounding the runoff that empties into your pond. The first step is to inspect the watershed and shoreline for signs of erosion. Grass should be established upstream of the pond on any exposed, bare soil. In our area, it is hard to beat using common bahiagrass. If you want a more attractive grass, try using common bermuda. Both seed can be found easily (for a very reasonable cost) at your favorite local feed store.

If it is not the erosion of soil into your pond but heavy rainfall or unwanted fish are the cause of muddy pond water, the root cause is negatively charged clay particles. Much like when you couldn’t get the negative ends of two magnets to touch when you were a kid, the same charged soil particles don’t want to touch and therefore will not settle out of a pond. We can easily remedy this with the addition of positively charged particles that will bind with the opposite charged soil and settle out.

Pond owners have a couple of options to help: agricultural limestone, gypsum, and alum. Our East Texas ponds are typically a little on the acidic side of the pH scale, so I always recommend starting off with the addition of agricultural limestone. Liming a pond, just like liming a garden or hay meadow, raises the pH (lowers the acidity), and can often help to clear up muddy water.

Be sure to add agricultural limestone as it works slowly and will not kill the fish. There are several forms of lime available, and they certainly work much faster than agricultural lime. However, changing the pH too quickly will cause tremendous stress on the fish in your pond and likely kill them.

Go slow and use agricultural limestone.

Now if the agricultural limestone did not clear up the muddy water to your satisfaction, I next recommend using gypsum. Gypsum is a naturally occurring soft mineral and is the major component in the sheet-rock that covers the interior walls of most buildings.

Available in a bulk, gypsum does a tremendous job of binding with the negatively charged, suspended clay particles in your water. Once bound with the clay particle, it precipitates out onto the bottom of your pond.

To determine exactly how much gypsum you would need, you need to take some measurements. First you need to determine the volume of water in your pond. We measure this in “acre-feet”. One acre-foot of water can be visualized as 1 acre (think of a football field) that has one foot of water on it. To determine this on your pond, multiply your pond’s surface area by the average depth.

Next, in several 1-gallon containers that has your muddy pond water, add 1 tablespoon of gypsum to one, then continue incrementally adding gypsum until you find the minimum tablespoons of gypsum it takes to clear up a gallon of your muddy pond water in 12 hours. For every tablespoon of gypsum to a 1-gallon container, add 80 lbs. of gypsum for each acre-foot of water in your pond.

This may seem difficult at first but can be very simple to execute. If you wish to learn more about farm pond management, the Angelina County office of the Texas A&M AgriLife Extension Service will host a farm pond management seminar on Tuesday, May 18 at 6:30 pm. There is no fee for the seminar.