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How to Clean a Pond in 8 Basic Steps

A “Complete Cleanout” is a process where you completely remove all water and living organisms (fish, plants, etc.) out of the pond; clean as needed; refill and add life back into the pond. This may be done yearly or every other year or more depending on your fish load and the amount of debris & sludge that have accumulated in your pond. This should be done when the fish are active- usually from April through September- depending upon the weather conditions and the region you live in. If you do not have fish, then the timing is not as crucial. If done too early or too late in the season, your fish may not be able to acclimate to the new water conditions and could possibly expire. Also avoid extreme weather- too cold or hot- a partly sunny mild day would be perfect for cleaning your pond.

Items Needed for a Complete Cleanout:

• Cleanout Pump and Hose (to evacuate the old water away from the pond)

• Nets– long handle Skimmer Nets (fine) and Pond/Fish Nets (to capture debris and fish)

• Water Hose and Nozzle– Hose needs to be long enough to reach all areas with a strong nozzle 

• Fish Tank or Container, Netting & Aeration Pump (to hold fish, cover and aeration)

• Water Treatments– Beneficial Bacteria, Sludge Reducer, Water Conditioner, Fish Treatments (if needed)

Step One: Evacuate the Water. Attach hoses and fittings to pump as needed. Place the cleanout pump submerged inside the pond at the lowest depth. Hose should be long enough to extend to an area where the water will not drain back into the pond- great for fertilizing the landscape & garden. Plug in pump and start to drain out the pond water. Make sure your fish are not getting sucked into the pump- cover pump intake with a rigid plastic mesh pot if needed.

Step Two: Fill Fish Tank. If you have many fish, use multiple tanks or a larger one depending upon your situation. A shady site is best place to keep your tank while you clean the pond. Add some pond water into this tank about ¼ to 1/3 fill, then add the rest to fill tank almost to the top water from the tap(add “water conditioner” or “stress coat”. Add a small submersible pump or aerator with air stones to provide oxygen while the fish are being housed.

Step Three: Catch Fish. Wait until the water drains (this may take several minutes or hours) down to a foot or so in order to catch the fish in a smaller area. Turn off / unplug the cleanout pump. Use your pond net to catch fish and immediately place in the fish holding tank. The tank(s)need to be covered with netting and very secure as fish will try to jump- koi more so than goldfish.  Continue to catch all fish and other life you want to save. Examine your fish for disease and damage- treat if needed while they are in the tank. Pond plants can be put into this container or use additional if needed, especially if you need to treat your fish.

Step Four: Clean Filters. This can be done before you catch the fish if there is a long drain time or after the fish have been removed. Take out filter pads and media. Clean off sludge, algae and debris with water using your strong hose nozzle or pressure washer. Rinse several times. 

Step Five: Clean Waterfall and Stream. This can be started while you wait for the pond to drain down before you catch fish. I start at the top of the waterfall / stream area and work your way down toward the pond. First remove by hand as much as you can large patches of algae, debris, sticks, leaves and needles. Cut back or tidy up any plants in this area. Then use your spray nozzle or pressure washer (be careful not to blow holes in the liner!) to rinse out the waterfall and stream area Continue to spray water washing the muck and debris into the pond basin. You can move rocks around to get debris trapped under them. 

Step Six: Clean the Pond. Now it’s time to “clean” the pond basin area. Remove by hand or use a net to collect larger patches of algae, debris, sticks, leaves and garbage from the entire pond starting in one area moving to the next until you are done. Cut back and /or remove dead leaves on existing plants. This may take several minutes to hours depending upon how much debris is present and how big your pond is. Like with the stream, use a spray bottle with white vinegar in it to spray on algae if needed. Scrub rocks as needed. Or use a pressure washer- With Care-you do not want to blow holes in your liner! Continue to spray water on the rocks and in between the cracks from top to bottom and drain it out until the water is mostly clear.  This may take several hours.

Step Seven: Fill the Pond. Once you feel that the pond, stream and waterfall area is “clean” enough then begin to fill the pond with water. Filling the pond with water may take several minutes, hours or days (if it is huge). Add water treatments to your pond as needed and directed on the bottle. Water Conditioners remove heavy metals and chlorine from the new water you are adding. Beneficial Bacteria is very important to add back into the pond, to breaks down wastes and needs to be recolonized into the pond for a healthy environment. 

Step Eight: Add Fish, Turn On. Net the fish in the tank and gently put back into the pond water. You can add fish when there is enough water to cover their top dorsal fin of your largest fish or 1 -2’ of water depth. Keep filling until the pond and filters are full or at optimum level, plug in / turn on the pump. Continue to add water as needed while the waterfall and stream area are filling.

This can be a long, dirty process but not completely unenjoyable. You get to know more about the workings of your pond and connect with your plants and fish in a hands on manner. Fish get used to this process. I have been cleaning ponds for over 10 years and my client’s fish “knew” me and seem to acclimate fine to this process. Be smart, monitor fish frequently and you will do fine.

If you don’t feel comfortable doing this process, then hire a professional like Nature Perfect Landscaping, Pond Maintenance Division. They have several years of experience, like getting their hands dirty while being gentle with your fish!

Call 360-280-5116 to schedule an appointment.

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