How to keep your pond clean

A small pond can greatly enhance the beauty of your backyard or garden. However, maintaining a clean pond is quite a challenging task. You can keep the pond clean using natural methods such as barley straw, plants, and biological filtration systems. Additionally, you may use ultraviolet water sterilizers, pond treatment chemicals, or gypsum to keep the water clear. Lastly, make sure to drain the pond at least once a year, relocating all plants and fish, and replacing the water with fresh water.

Clean the pump filter regularly. Most filters need to be cleaned once a week. Typically, you can remove the filter, rinse it with a hose, and reinstall it. However, you should follow the cleaning procedure and frequency recommended by the manufacturer.

• If you notice any leaks or strange noises from the pump, it's time to clean the filter.
• If the filter has a pressure gauge, clean it when the pressure level reaches 1.8 to 2.3 kg.
• Not cleaning the filter regularly will reduce its efficiency and compromise the cleanliness of the pond.

Manually clean the pond. The most cost-effective yet time-consuming way to remove algae is to check the pond daily or every few days. If algae are present, you can use a rake or long pole to scoop them out directly. This method requires regular inspection and careful observation of the pond.

• Remove leaves and debris floating on the surface. You can remove most fallen leaves, twigs, seeds, and weak plants using a debris net. This net has a mesh bag and a long handle, specially designed for cleaning ponds and pools. You can easily find them at most pool supply stores.
• Clean the bottom of the pond. You can use a pond vacuum to suck up leaves, algae, sludge, and other debris that accumulate at the pond's bottom. These vacuums are usually available at plumbing and pool equipment stores.

Feed fish properly. It's important to select the right food and feed fish in moderation. If you have fish in your pond, feeding them high-quality food will help prevent algae growth because the fish will consume most of the food, and their waste will be minimal. To ensure the fish eat all the food provided, check the water's surface for leftovers about 20 minutes after feeding.

• If there is leftover food, you've overfed the fish. Gradually reduce the amount of food until no food is left on the surface. Excess food will decompose and provide nutrients for algae growth.
• Choose food based on the type of fish, though most commercially available food works for various species. If you're unsure what to feed your fish, ask the supplier or a vet.
• Reduce food quantity during the fall and winter. In these seasons, fish metabolism slows, and they eat less.

Use biological filtration devices. Biological filtration systems utilize bacteria to break down organic waste that forms in the pond. You can choose an in-pond filter or an external filter.

• An in-pond filter comes with a pump connected to a water inlet. This type of filter is easy to install, but to clean it, you must remove the entire system from the pond.
• An external filter is easier to clean, but it can be challenging to find a unit with the right power, as these are primarily designed for pool water filtration.
• The bacteria in a biological filter are also naturally present in the pond, but their population is often too small to filter all the accumulated toxins.
• You should choose a filter that can process twice the volume of the pond's water. For example, if your pond holds about 1500L of water, purchase a filter rated for 3000L. A filter rated exactly for the pond's volume may not achieve optimal water filtration performance.
• The filter should be able to process all the pond's water in about two hours. Check the pump's speed and compare it to the pond's water volume to select the appropriate filter.

Add barley straw to the pond. When barley straw decomposes, it releases a chemical that helps prevent algae growth. One bale of barley straw can treat about 3780L of water. This means you only need a tenth of a bale to treat a pond with a capacity of approximately 400L. The best method is to place the straw in mesh bags and roll them into small balls, similar to tennis balls, before adding them to the pond.

• You can also use barley straw extract as a substitute. A tablespoon of extract typically treats about 190L of water. Increase the dosage if the water condition does not improve after a week.
• Barley straw is available at many aquarium supply stores.
• It is safe for fish ponds.

Planting certain types of plants in the pond. You can introduce floating or submerged plants into the water. These will naturally inhibit algae growth and keep the pond clean.

• Planting floating plants. Species like lotus and water lilies, with their leaves on the water's surface, help reduce the pond's exposed area, while absorbing nutrients that would otherwise fuel algae growth.
• Submerged plants, such as water moss, dogtail algae, or seaweed, provide oxygen to the water and help prevent algae bloom. These plants can be anchored to rocks or placed in pots with added weight, then submerged into the pond.

Using chemicals to treat water. Water treatment chemicals are designed to prevent and eliminate algae. They are safe for fish and invertebrates like snails but can harm tadpoles. Each chemical comes with specific instructions that you must follow for safe use.

• After using these chemicals for a while, the water may need further treatment. Continue applying the chemicals if you notice algae returning or if the water turns green again.

Using calcium sulfate. Calcium sulfate, also known as gypsum, is effective in breaking down sludge that accumulates at the bottom of the pond. Apply gypsum evenly across the pond's surface at a rate of about 240kg for every 1233 cubic meters of water.

• Gypsum can be purchased from companies specializing in the production of gypsum or from stores selling building and interior decoration materials.
• Gypsum is harmless to both fish and plants.

Installing a water circulation system. Circulating water helps reduce algae growth and prevents debris buildup. Consider installing a fountain or artificial waterfall near the pond to ensure water circulates back into the pond. This system can be placed in the center if the height is greater than the depth of the pond.

• If installing a fountain or waterfall under 1 meter high, place the pump on the ground near the waterfall. For waterfalls 1.5 meters or higher, the filter should be positioned directly behind the waterfall at the same height as the peak.

Using ultraviolet (UV) sterilization equipment. This device sends water through a compartment that exposes it to ultraviolet light, which kills suspended algae in the water (except filamentous algae). This allows for easy removal of dead algae.

• The UV sterilization unit can be installed alongside mechanical or biological filtration systems.
• Since ultraviolet light is harmful to the eyes, the UV bulb will be enclosed in a protective casing. Be sure not to remove this protective casing.
• A UV sterilizer with a 8-10W bulb can treat approximately 3780L of water.

Drain the pond when necessary. If the pond's bottom accumulates too many fallen leaves and sludge that can't be cleaned using a pond vacuum, you should completely drain the pond. However, if you can easily remove debris from the bottom, draining the pond may not be necessary.

• It's recommended to drain and clean the pond thoroughly at least once a year. The best times are in spring (to remove debris accumulated during the winter) and autumn (to prepare the pond for winter).

Pump water out of the pond. You can purchase or rent a pump with a suction hose long enough to reach the pond's bottom. To avoid wasting water, consider using the pumped water to irrigate your garden.

• Transfer some water into large containers, inflatable pools, or storage tanks if you have fish in the pond. Temporarily place the fish in these tanks while draining the pond.

Move the fish out of the pond. After pumping most of the water out, leaving just enough for the fish to swim and for you to walk through easily, transfer the fish into temporary tanks. Typically, leave about half a meter of water remaining in the pond.

• Use a net to catch the fish and transfer them into the temporary tanks.
• It's a good idea to cover the temporary tank with a net to prevent the fish from jumping out.

Finish draining the pond. Once the pond is drained, you can begin relocating the plants. If the plants need water to survive, temporarily place them in a tank. At this stage, you can remove dead plants and fallen leaves.

• Clean the pond thoroughly once it is fully drained. Use a high-pressure water spray to wash away the sludge from the bottom and edges of the pond.
• Avoid using detergents or harmful chemicals to clean the pond.

Refill the pond with water. Replace the old water with fresh water and add a dechlorinator. The dechlorinator will remove chlorine from the water, which is crucial since high levels of chlorine can be fatal to fish. After replacing the water, you can reintroduce the plants and fish from their temporary tanks into the pond.

• You can purchase dechlorinator solutions from pet stores. The amount to use depends on the pond's volume. Be sure to follow the manufacturer's instructions for specific usage.
• To help the fish adjust to the new water environment, replace about 4 liters of water from the temporary tank with 4 liters of fresh water every 5 minutes. After approximately 30 minutes, you can return the fish to the pond.