No matter how large or how few fish live in them, ponds can get dirty quickly. The water can become cloudy, green or even stagnant. Stagnant pond water not only smells bad, but it is also a potential breeding ground for biting insects like gnats. Regular pond maintenance can help keep the water clean and clear. Pond maintenance tips are the same for any type of pond, whether it is for commercial fish farming, swimming or raising domestic fish like koi.
Check for the cause of any cloudy water. Scoop pond water up with a clean, clear glass jar. Put the jar of pond water in sunlight for 4 to 5 days. Algae will move about constantly in the water and will turn the sides of the jars green or brown. Silt will settle at the bottom of the jar and will not move about.
Treat the pond for excess silt. Throw in 45 kg of hay to treat silt caused by clay soils. Treat a pond with hay no more than five times a year, treating as needed. For other types of soil, add agricultural lime or agricultural gypsum as the manufacturer suggests.
Check the sides of ponds for erosion, which could add silt to the pond water. Some rodents cause holes or crumbling sides. Repair the sides of the pond with tight-fitting rocks like or fencing that does not rust. The rocks or fencing will discourage animals from digging. Hire a pond contractor to do the work if necessary.
Remove excess leaves and pond weeds with a pond skimmer or rake. Rotting leaves or weeds can cause the pond water to turn brown and cause a large build-up of ammonia that can be fatal to any fish or creatures living in the pond water. Rotting leaves and weeds can also help trigger a population explosion of algae. Taking leaves off of the pond's surface is enough. Digging to the bottom of the pond is not necessary.
Pond water that is especially muddy and has large holes in the pond sides is often due to cattle coming down to drink. Talk to anyone in the community that has cattle to see if this is the case, and set up a fence to keep cattle away.
Avoid using pesticides to kill rodents that might be damaging your pond. The chemicals can leak into the water and poison your fish.