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How to Effectively Clean Your Pond Water and Filter

How to Effectively Clean Your Pond Water and Filter

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Cleaning your pond can seem like an intimidating task, but that’s no excuse for neglecting it and letting it turn into an eyesore.

That said, pond cleaning doesn’t have to be an overly-complicated process. So, we’ve prepared the following tips on how to clean pond water to help you keep your pond charming as ever.

Why Clean a Pond?

If you don’t clean your pond regularly, it’ll gradually become unhealthy and dangerous for its inhabitants. At worst, your aquatic plants and fishes can die due to the buildup of dirt, sludge, debris, leaves, algae, and many more.

This is because the wind carries all sorts of things that fall into the pond. Once in the pond, they decompose and release the natural chemical nitrate.

While it’s safe for a pond to have a low level of nitrates, too much of it will negatively impact the water quality, which can put your pond fish in danger.

The signs of high nitrate levels in the pond water are:

  • Algal bloom or “green water” from the buildup of algae
  • A sharp unpleasant odor
  • Cloudy or foggy water

The signs of nitrate poisoning in fish include:

  • Fish breathing problems like gasping or spending lots of time on the water’s surface
  • Fish swimming in a weird way
  • The fish seem tired or lethargic
  • The bodies are bent or curved
  • They lose color or become pale

On top of that, a dirty pond can also be a mosquito breeding ground, which is a potential health hazard to humans as well as pets. A neglected pond can only compromise your and your loved ones’ safety.

How to Clean Pond Water With Fish in It

Do you want to clean your pond without the hassle of removing the fish? Or maybe you don’t have anywhere else to put the fish into?

You can clean your pond without taking out the fish and draining the pond water. That’s not to mention that keeping the original pond water allows beneficial bacteria to stay, which helps in the pond’s natural filtration system.

1 – Skim the Pond Water’s Surface

Using a pond net, pond rake, or pond skimmer, remove the water’s surface debris like trash, leaves, twigs, sticks, dead insects and plants, and other floating bits.

If you use a pond net, make sure it has a broad head and a fine mesh to allow it to skim different sizes of debris effectively.

In addition, pay attention to floating or clinging string algae. String algae are green hair-like strands of algae that protect the fish and help combat green water.

Nevertheless, if left unchecked, the algae could deplete oxygen from the pond. You can use your hand, a brush, or the pond net to remove them from the water.

You can also invest in a pond skimmer. A pond skimmer is a device that automatically collects surface debris so that it won’t sink and decompose on the pond floor.

The less debris on the water’s surface, the healthier the pond is for the fish.

2 – Clean the Pond Floor

You need to clean the bottom of the pond to remove the thick sludge that may have accumulated. The sludge includes garden debris, fallen leaves, dead pieces from aquatic plants, algae, uneaten fish food, and fish waste.

Use a pair of pond gloves, a pond net or scoop, or a rake. Manually remove the debris that has settled on the pond floor.

Alternatively, you can use a pond vacuum cleaner. Pond vacs make it easier to remove the dirt from the bottom by using suction power to clear away the pond’s accumulated sludge.

Pond vac models come in different shapes and sizes and work in various ways. Several models have cleaning attachments specialized for hard-to-reach spots in the pond and dealing with varied types of debris.

If you have a deep pond, remember to choose a pond vac model with an extendable handle for more effective cleaning. Likewise, ensure that the vacuum retains suction power even at certain depths.

Moreover, pond vacuums are effective in removing sediments. Sediments are suspended clay particles that regularly accrue over time and may cause muddy pond water.

Finally, there’s no need to drain the water when vacuuming the pond. In addition, you don’t have to worry about your fish since they can instinctively move away from the pond vac when needed.

3 – Install a UV Clarifier or a UV Sterilizer

A UV clarifier and a UV sterilizer emit ultraviolet light from a bulb that kills single-celled algae, bacteria, and parasites. Both are also effective in curing algal bloom or “green water,” which occurs when a pond reaches high levels of certain plant nutrients paired with sunlight.

The clarifier and sterilizer differ in the strength of their UV lights. A UV sterilizer has higher wattage and a slower flow rate, which is the total amount of time bacteria are exposed to UV light.

Install a UV clarifier to control your pond’s green water. Nevertheless, you should still ensure that the pond has other measures to control algae, such as partial shade and plants that help to minimize algae.

Additionally, the UV clarifier’s power is enough for most ponds to defeat green water. For other ponds in hot and sunny areas, use a UV sterilizer to eliminate green water, along with bad bacteria and parasites that cause fish diseases.

Despite the UV sterilizer’s higher UV power, large waste particles can get stuck and trapped inside the device, which can make it useless. On the other hand, the UV clarifier has a bigger content chamber and therefore has a lesser possibility of solids getting trapped.

How to Clean a Pond Filter

A pond filter removes harmful chemicals and toxins, solid particles, and debris. However, you also need to clean it, or else debris and solid materials could get clogged inside the device.

There are several types depending on the waste they can filter. To help you, check out the following guide:

1 – Mechanical Pond Filter

A mechanical pond filter removes suspended solid particles, physical debris, and sludge. It doesn’t interfere with chemical filtration.

One example is a pond skimmer. Pond skimmers remove a lot of the pond water’s surface debris.

A skimmer is composed of a filter pad and a rigid basket. The waste goes through the filter pad and stays in the skimmer’s basket instead of littering the pond. To clean a skimmer, you just have to empty its basket and rinse the filter pad.

Generally, mechanical pond filters are made up of filter pads, sponges, and cartridges. Use a garden hose to clean the parts individually.

In addition, you can use tap water to clean the filter, but many experts recommend pond water. Do this cleaning routine once a week.

2 – Biological Pond Filter

A biofilter or biological pond filter colonizes good bacteria that break down the toxin ammonia to nitrate, then to nitrate. In turn, the pond’s aquatic plants absorb the nitrate.

The biofilter also serves as a shelter for these bacteria. In addition, water that passes through the device goes out free of debris and toxins.

To clean, be careful with the good bacteria housed inside the filter. You should use pond water instead of chlorinated or tap water so the bacteria won’t die.

Finally, cleanse the biofilter until you wash off the clogged mud. Clean the device once a year.

3 – Chemical Pond Filter

This filter deals with the removal of toxic chemicals in the pond water like ammonia, copper, hydrogen sulfide, and nitrate. It has a stronger chemical filtration ability compared to all the other filter types.

The chemical pond filter uses activated carbon to absorb the pond’s toxic chemicals. When the pond water becomes cloudy, it means the carbon has expired.

You should replace the carbon right away if you see that the water is cloudy. Moreover, wash the chemical pond filter and its components once a week.

Also, remember to do annual maintenance of the filter.

4 – Pressurized Pond Filter

With the pressurized pond filter, pond water is kept clean and clear. It’s a water-tight circular canister that uses pressure to trap pond water inside, then filter it using sponges.

In this case, the filter doesn’t need a lot of attention. You just have to ensure to regularly replace particular components to keep the filter working effectively.

A pressurized pond filter has many parts, including a UV bulb and filter media pads. These two degrade over time, so make sure you replace them once a year.

Remember to unplug the filter from its power source before replacing its components.

As for washing the device, you can disassemble the components and cleanse each individually.

Final Thoughts

There are many reasons why you should clean your pond regularly. Not only does a dirty pond become unhealthy for its plants and fish, but it can also become a health hazard for you.

To clean pond water, you should first remove the physical debris from its surface. Then, clean the pond floor manually or by using a pond vacuum.

Lastly, you can likewise use a UV clarifier or a UV sterilizer to kill algae, bacteria, and parasites that are harmful to your fish and aquatic plants.

Another step is cleaning the pond filter which removes the pond’s physical debris and toxic chemicals. There are different types of pond filters, each with its own maintenance and cleaning processes.

Remember to clean and maintain the pond filters regularly to keep them working effectively.


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Sunday 17th of September 2023

I cleaned the filter Friday. Today is Sunday and my pond water still green. The water coming from the filter to the pod is green. How long will be like this and or, is my filter perhaps damaged. I replaced the uv light and the sponges. Do I wait few more days or the filter is maybe too old.