How to Clean Pond Water

So, your pond water is all cloudy, or green, or brown or has string algae floating on it? Getting your pond water clear will give you a great feeling of satisfaction. Or, if your pond is a natural swimming pool, it’s a lot nicer if it’s clean and clear.
The green is usually caused by algae. Here’s a number of steps that can bring things back into balance, help remove algae from your pond and also deal with other issues.
It can look gross, but stagnant water tends to be a natural breeding ground for all kinds of flora. This is actually part of a natural process in which a standing open body of water gradually turns into a swamp, and then ultimately back to rich soil(or into peat and/or coal), over many hundreds or thousands of years(or longer) . Organic matter keeps growing, dying & piling up at the bottom year after year, after year, eventually filling in the pond.

If conditions are right, occasionally this process can even involve the creation of floating islands, such as those at the Chippewa Flowage in Wisconsin. Some of these islands are several acres in size and have mature trees growing on them. It’s an interesting phenomenon.

However, with some fairly simple techniques, you can often stall these natural processes so that you can fully enjoy your pond and keep the waters clear during your time here.

Test Your Water
If it isn’t immediately clear what the cause of your water quality issues are, doing some basic water testing makes a lot of sense. You can often buy pond water test kits for very little money. You’ll want a kit that will at least test for pH, Ammonia, nitrites and phosphates. The results of the test will at least point you in the right direction.

Often, a little bit of algae or discoloration is normal
Your pond is usually a complex living, breathing ecosystem full of fish, plants, bacteria as well as other life that’s too small to see with the naked eye.

Any imbalances in your pond’s biology can cause various kinds of water clarity issues. If you want crystal-clear water, your first step is to determine what kind of problem you have. You also have to assess how realistic your goals are with your specific pond. Some systems may have complexities that make it extra challenging, such as local soils, runoff and more.

Brown or brown & cloudy water.
This can be caused by tannins from leaves, mulch and/or debris and/or silt from any surrounding gardens or soils. If The issue is tannins, the water will have a brownish tint, but will still be mostly clear.
If the pond is brown and cloudy, likely silt or sludge has been stirred up from the bottom. It’s ok to have cloudy water after a heavy rain, or just after the pond was built. If it’s ongoing, perhaps using a flocculant may help.

Green Water (Single-Cell) Algae and String Algae
This algae is tiny single-cell organisms that live in your pond and turn the water cloudy green. You can usually not see very far into the water when this happens.

Algae isn’t necessarily bad; it’s just one of nature’s ways of dealing with excess nutrients. Single-cell algae arrive in your pond as tiny airborne spores. These spores like low oxygen water, and feed on nitrites and other phosphates etc.. They then rapidly multiply which can quickly make your water cloudy.

This algae won’t hurt any fish. Some pond owners don’t mind a green pond. However, many folks prefer clearer water in their pond. It usually feeds on excess nitrites in the water.

Brown and green water can be greatly reduced, or eliminated by introducing beneficial& natural bacteria and oxygen into the pond.
Shop Cleaning Pond Water

String algae is is very common in backyard fish ponds and waterfalls, especially where there are hard surfaces underwater. It’s slimy, slippery and green, and you might even be able to pick it up with a skimmer, or your hands. String algae won’t turn you water green. Instead, it clings to rocks, liner and plants, or can float on the surface.

String algae is normal and you’ll always have a little bit of it hanging around. However, if you get a lot of it, it’s a sure sign that things are out of balance. If there’s lots on the surface, it can block sunlight into the water and greatly impair the ecosystem.

How to reduce, or stop it?
Beneficial bacteria also consumes nitrites and with the right types, will also consume the decaying matter in the water and the goo that accumulates at the bottom of the pond. The key is having the right types and enough of it so that all the nitrites are consumed and none is left for single-cell algae – starving the algae so it doesn’t grow or multiply & make your water all green.

Beneficial aerobic bacteria in the right format will add lot of good bacteria to the water and can also add lots of oxygen to the water, in a way that can’t be easily done by aeration. The best part is that it’s very safe & you don’t have to worry about adding too much – unlike with algicides, an overdose won’t kill your fish or plants – and it’s safe for pets and humans.

How does it work?

It’s really simple to add it manually. Just toss some tabs or sachets in key areas in you pond at the prescribed intervals and amounts. Exact amounts will depend on the size of your pond and a few other factors.

You can also add a variety of aquatic plants to help starve string algae, if you choose.

Aeration
Various pond sizes, from small decorative ponds to larger ponds, can definitely benefit from aeration and/or agitating the water. This can go a long way to keeping your pond clean. All water can hold a certain amount of oxygen. The more active the water, the more oxygen it will hold. In stagnant water, the oxygen floats to the surface and the bottom water layer loses oxygen. When you aerate the pond water from the bottom, this adds oxygen to the bottom layer and ensures that all of the water has a proper amount of oxygen. It also helps turn the water over. Low oxygen levels can suffocate fish and can contribute or lead to other problems, such as algae blooms, etc.

There’s a few approaches to aeration; For a fairly deep pond, bottom diffusion aeration works well. This diffuses the water from the bottom, forcing the water up toward the surface where it can access more oxygen. If your pond is six feet or deeper, a bottom diffusion system is recommended.

For shallower ponds, surface aeration is an option, such as a waterfall. This will this help agitate and aerate the water, but is also nice to look at with a relaxing sound.

Thirdly – certain products added to the water, such as Eco-tabs can really increase water oxygen levels and don’t require expensive equipment or intensive maintenance.

Filtration

Your pond can benefit from two types of filtration: biological and physical.

Physical Filtration

Physical filtration works the same way a pool skimmer works. It removes leaves, fish waste and other floating debris from the pond before it has a chance to cause problems. The best type of physical filtration is a pond skimmer. These skimmers suck debris into a basket that you can easily empty as needed. There are 2 types of skimmers; built-in and floating. Depending on your pond type, one may work better than the other for your situation.

The drawback is that the equipment does need to be installed, which could be very involved and it will need electricity. It will require regular maintenance, and in northern climates, where the water freezes you may need to drain and/or remove and store the system each fall and reinstall/restart it each spring.

On smaller ponds, you can also do some of this manually with a skimmer net. However, this requires consistent and regular time & attention.

Biological Filtration

Biofilters are structures or tanks filled with nooks and crannies or anything else with lots of surface area – where beneficial bacteria can hang out and reproduce. Having a large biofilter will help those all-important bacteria to thrive.

There’s several types of Biofilters, such as Biofalls: a plastic container that holds filter media and forms the beginning of a waterfall. Water flows into the bottom of the falls, swirls around the bacteria-rich interior, then spills out the top.
Bioballs – small plastic balls with lots of nooks and crannies, as well as a center tube that allows them to be strung together.
Rock filters- landscape or other rock, or crushed stone, or coarse gravel with lots of small spaces for bacteria growth.
Other types, such as urn filters and so on. Generally, go as big as your space and budget will allow. More biofiltration usually means more beneficial bacteria, which means clearer water, less algae and happier fish.

If you have filtration, your biofilter should be separate from your physical filter. Although some filters claim to offer both kinds of filtration in a single unit, it’s better to have two filters so you can clean debris from the physical filter as often as needed without disturbing the bacteria in the biofilter.

Leave the power washer in the garage
If you get the urge to clean the rocks in and around your pond, it’s better to do it a limited amount of cleaning by hand. Removing some of the string algae from your rocks, can be very helpful in algae control. However, there’s a big difference between manually removing some gunk and using pressure washer. Washing your rocks will affect your ecosystem that has taken a long time developing. These ecosystems are complex and we can never replicate it with chemicals, or other methods, so we don’t want to risk damaging it too much. Besides, the algae will likely come right back.

Cut Back on Fish Food
Your fish won’t get fat if you overfeed them, but too much food will cause other issues. It adds a lot of organic matter to the water which will then biodegrade, producing more sludge, nitrites, sulfides and more.

You really don’t need to worry about your fish going hungry; they naturally will eat algae, mosquito larvae and other materials in the pond. In nature, they will achieve balance without our intervention.

Having The Right Plants
Some ponds will naturally have the right plants. However. you pond may need some. Plants can help keep water temperatures cooler and provide much-needed shade and protection shade for fish and other aquatic life.

Sometimes floating plants can be a great option. Not only are these beautiful, but they also restrict the growth of algae and eat up some of the nutrients that algae need in order to grow. Some plants even add extra oxygen to your pond water.

Keep numbers of Fish at a healthy level
Fish produce waste, which adds to the organic matter in your pond. Too many fish means too much fish waste, which means gross water. So, how many fish should you have? The answer is a little more complicated than a simple number of fish per gallon. It all comes down to how well your pond ecosystem handles the fish waste. The bigger the biofilter, the more fish waste you can process.

If you’re getting these symptoms you may have too many fish;

Difficulty keeping the water clear, despite regular doses of beneficial bacteria
Too much string algae, despite lots of plants in the pond
High ammonia levels
Dying/Sick Fish
If you have too many fish, maybe it’s time to improve your filtration system (i.e. install a larger biofilter and/or skimmer), or find new homes for your fish.

Before Adding Algicide
Algaecides are popular options for cleaning green stuff from ponds. They can be fast but……

They don’t treat the main cause of your water problems, just one of the symptoms. Excess nutrients and other causes should be dealt with first before using any algicides. Ultimately, natural methods which keep things in balance is the best approach.

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