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Keeping Pond Water Clear

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murky pond water

If your pond it beginning to look like a vat of split pea soup it is time to clean it and begin using some maintenance techniques to keep it that way. This is a guide about keeping pond water clear.


Solutions: Keeping Pond Water Clear

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Tip: Clearing Murky Pond Water

Water lily in pond with fish below.There is a growing trend in gardening of adding water features to the yard and garden. Installing a pond to your landscape gives your garden a sense of peace and serenity and makes a delightful addition for backyard wildlife. Neglecting to maintain it, however, can quickly turn your tranquil pond into a smelly, murky headache. Here are some ways to clear up murky pond water.

Too Much Algae

Murky brown water is almost always caused by an excess of algae. Some types of algae float to the top and "bloom," while others remain suspended in the water column, causing the water to look dark. If your pond contains fish, chemical controls may not be safe for them. One safe and economical solution is to submerge barley straw wrapped in netting into the water. As is decays, it releases a chemical that inhibits algae growth. Anchor it to the bottom with a brick or large stone and change it every 6 months.

Too Many Fish

A pond that is overstocked with fish is prime for algae problems-excess waste (nitrogen) stimulates algae growth. Most pond gardeners calculate the number of fish for their ponds according to the surface area or the number of gallons of water it holds. This might work to start with, but it won't be accurate for long. Remember, fish grow! Consult with your fish supplier to find out how large your fish will grow under ideal pond conditions. Don't forget to add snails, bottom feeders and if possible, some freshwater mussels to help gobble up the algae. According to the USDA, non-aerated ponds should have no more than one, 12" fish per 10 square feet of surface area. (To calculate surface area multiply the length x width of your pond). Aerated ponds can have up to one, 12" fish per 2-3 square feet. They also recommend that the average hobbyist stay well below these guidelines.

Too Much Fertilizer

Fertilizer leeching in from the lawn or nearby flower beds can overburden the pond's nitrogen load. Avoid using fertilizers where there is a risk they will contaminate your pond water. Traditional fertilizer mixes will promote algae growth, so use a soil mix designed for potting aquatic plants when adding them to your pond. Even then, try to keep the mix confined to the plants by lining underwater pots with burlap and weighing down topsoil with gravel and rocks.

Too Much Sunshine

A lot of sun may be great for the rest of your garden, but too much sunlight streaming into your pond causes excess algae. Site your pond strategically near buildings and fences which will cast a shadow over your pond for at least part of the day. The addition of surface plants like water lilies will also provide shade and help hold down the water temperature (algae love warm water). Add a variety of underwater oxygenating plants like Elodea, Microphyllum and Ceratophyllum (1 bunch per 8 inches square). They will help keep water oxygen levels high and algae levels low.

Too Much Tap Water

The chemicals that sterilize our tap water can actually work to increase algae blooms. When you refill your pond, try to fill part of it with some water from a stream or even another pond. Nature's water contains insects and other organisms that will help keep the algae population down.

Too Much Plant Debris

It's important to keep your pond free of decaying vegetation. As plant materials decay under water, they release nutrients that stimulate algae growth. When your pond freezes over in the winter, this decay can also cause toxic gases to build up under the ice. Trim dead or dying foliage from plants located around the margins of your pond. If overhead trees are a problem, consider erecting a frame around the pond so you can cover it with a canopy as necessary or clean leaf debris out daily with a large net.

Not Enough Patience

It can take several months for a new pond to reach an ecological state of balance. In the first few weeks-sometimes months, your pond's water may look murky and even when in perfect balance, it won't be 100% clear any more than a pond in nature would be. The worst thing you can do during this time is keep cleaning and refilling your pond in an attempt to achieve clear water. Every time you do this, the pond has to start over trying to reach a state of balance. Be patient! It will be worth the wait!

By Ellen Brown

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Here are questions related to Keeping Pond Water Clear.

Question: Koi Pond Water Murky

I have a Koi pond 11x10x3. The parameter are all OK (ph., nitrate nitrite, etc.). A glass of the water is good enough to drink, but I cannot see my fish as in the pond the water is murky.

By Brian M.

Question: How Can I Clear Up Murky Green Pond Water?

I have a new pond and have filled it from a neighbor's pond that is to be cleaned out. The water is pretty green and fuzzy looking. He has a woods near by, and was always fighting leaves (black settlement on bottom). He has used a lot of copper sulfate in the past. What would be best way to clear up the water? Any help please!

By Todd from Lima, OH

Question: Keeping Pond Water Clear

Q: I have a small fish pond in my front flower bed. It is under some tress so it gets lots of shade. In the past I tried electric pumps to filter the water but they would constantly get stopped up. I finally took the pump out and now just have the pond without any filter. Is there any product that will keep the water clear? I have cleaned the pond and put fresh water in it. I waited 3 days to put the fish back in so the water would not kill them. What is the best way to keep the pond clean at this point? I really don't get algae in the water but it is hard to keep it from turning dark. The liner is heavy plastic and the pond holds about 50 gallons of water.

Cookiepom from Owensboro, KY

A: Cookiepom,

All ponds need some cleaning and maintenance to keep the water clear, but once your pond reaches a state of balance, cleaning and maintenance should stay at a minimal. In new ponds, water is seldom clear for very long and changing the water frequently only delays balancing the ecosystem. The keys to a balanced system are 1) a pond of the proper depth, 2) combined with a good filtration system (biological or otherwise), 3) adding the appropriate amount of plants and fish, and 4) a little bit of patience. Several things could be causing your water to look dark and murky, including algae, bottom silt, and excess waste and decaying debris (falling from the trees overhead).

Make sure the soil on the bottom of your pond is covered with large pieces of slate, sand or gravel to prevent the fish from digging up the plants and stirring up silt. Encourage the growth of submerged plants like Anacharis, Cabomba or Vallisneria (good in shade), which will not only oxygenate the water, but filter out suspended particles. If you haven't added them already, snails, tadpoles and bottom feeding fish are also important partners in eating algae. You may not think you have an algae problem, but algae can't always be seen with the naked eye. It's usually the single-celled algae (suspended in the water) that are responsible for turning it that murky green color. Light, warm temperatures and calm water are really all most algae need to "bloom."

Adding surface plants, like water lilies, will keep the pond cooler and block out light to the algae as they grow. These plants, along with the submerged plants, will eventually kill off the algae by taking up the CO2 and nutrients they need to survive. In a small pond, you'll want to shoot for having at least 50-60% of the surface covered with floating plants. Also, most pond suppliers recommend that a pond with 50 gallons of water or less should contain no more than 2-3 gold fish to keep from overloading the waste cycle. Koi fish are not recommended for smaller ponds because they grow to large.

Good luck!

By Ellen Brown


Most Recent Answer

By Sue (Guest Post)05/09/2006

PetSmart sells squares of pond water cleaner. You get 3 for about 10 bucks. You just float these cleaners in your pond, they are about 10x10 inches. At first they float and eventually sink, they dissolve and you don't have to worry about removing them. Add a new pad every 3 months. They really keep the water clear and sparkling