How To Keep A Pond Pump From Clogging Up? [Best Methods]

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How To Keep My Pond Pump & Filter From Clogging Up? (Prevention Tips)

A pond pump at the bottom of a pond
Pumps are vital to keep ponds in tip-top shape, as they remove excess debris and prevent sludge buildup. / CC BY 2.0

A clean pond pump is a vital part of every ornamental pond. Pumps are responsible for clearing out excess debris and preventing sludge buildup, allowing clean water to circulate around the pond. Their mechanism for stripping water of waste also increases dissolved oxygen levels, which is highly beneficial to fish and aquatic wildlife. 

Eventually, every pump will need inspection and cleaning. A fully efficient self-cleaning pump that requires no maintenance whatsoever is still just a dream. Even the best ones can get clogged up over time, especially in heavily stocked ponds with thriving plants. The most common reason for pond pumps always getting clogged is simply a lack of thorough maintenance.

Ever heard of the phrase, “prevention is better than cure”? This applies to pond pumps too! Clogged pumps are rarely the result of an overnight occurrence, and are usually a consequence of weeks to months of dirt build-up. Fortunately, there are many other things you can do apart from routine cleaning to reduce pressures on your pump and keep it from quickly clogging up. These tricks will save any pond keeper a ton of time and effort as a dirty pump can have detrimental effects on ponds.

Keeping a “Clean” Pond

Debris in a pond
You should regularly remove debris, such as twigs or decaying plants, from your pond. Jeff / CC BY 2.0

An outdoor pond, by virtue of its nature, will never be totally clean in the usual, sterile sense. Cleanliness here refers more to water quality, a proper balance of nutrients, and a healthy relationship between pond inhabitants. Biomass should always be within the carrying capacity of the pond system. A balanced pond will rarely wreak havoc on the pump, allowing it to be even more efficient at maintaining optimal pond conditions.

Daily pond inspection and water quality testing is of absolute importance. A short visit to the pond is enough to make crucial observations and pinpoint potential problems. Look out for debris, which includes twigs, fallen leaves, and decaying plants on the pond’s water surface or bottom. Regularly removing these before they find their way to your pond’s pump can make a huge difference.

You must also be on the lookout for changes in fish behavior and reduced water flow. These can be indicators of a malfunctioning pump. Missing or dead fish may decompose on the pond bottom or find their way to your pump’s intake valve. Make sure to remove these as they can cause spikes in ammonia and nitrogen levels as they break down.

A pond net should always be on-hand so that you can quickly and easily scrape debris from the water’s surface. You can likewise make use of a pond skimmer or a waterfall filter, which will serve as tools for pre-filtering the water before it enters the pump and increasing aeration. These will not only trap debris, but also remove oils and foam in a more passive manner.

More Tips for Preventing a Clogged Pump

1) Keep the pump running

Dirty pond water
If you don’t keep the pond pump running all the time, more debris may settle on the pond floor or clog up the pump. Hänsel und Gretel, CC BY-SA 3.0, via Wikimedia Commons

Some pond owners choose to periodically switch off their pond pumps as a way to save on energy costs. This habit can be more costly in terms of time and manpower in the long run. Frequently switching a pump on and off can cause more debris to settle on the pond floor or get backed up in the pump, eventually clogging it up.

If intermittent use of a pump is non-negotiable, you will have to clean it out, along with the pond, more often. Frequently inspect its intake valves and remove any trapped materials. If you have time to dismantle the pump, make sure to fully skim its chambers as well.

2) Add beneficial bacteria

Goldfish swimming in a clean pond
Good bacteria play a major role in keeping pond water clean and prevent harmful nutrients from affecting your fish. Robert Couse-Baker / CC BY 2.0

Good bacteria can act as bio-remediators, breaking down harmful nutrients before they can accumulate and harm your fish. They play a major role in keeping pond water clean, especially in natural freshwater systems. In ornamental ponds, they aid in decomposing waste into minute particles that can enter the pump and filter without causing clogs.

In the absence of beneficial bacteria, organic matter decomposition times take significantly longer. This may have a domino effect on the rest of the system, causing persistently high concentrations of harmful nutrients if the decomposing materials are not removed. Large populations of these bacteria usually reside in the slime that lines surfaces within the pond’s interior.

If you regularly scrub your pond’s lining as a part of routine maintenance, bacteria may have to be re-introduced or seeded back into the pond. UV water treatment, the use of algaecides or antibiotics, and adjustments in water pH may also bring about their loss.

3) Pond sludge removal

Pond sludge
Sludge is often found at the bottom of high-density ponds and is composed of things like fish waste and dead algae. Remy Sharp / CC BY-SA 2.0

That foul-smelling mass of waste often found at the bottom of high-density ponds, especially in the absence of submerged oxygenating plants and bottom feeders, is known as pond sludge. This can settle in the deepest, least oxygenated parts of a pond. Sludge tends to be composed of fish waste, debris, decaying plants, uneaten fish food, and dead algae and plankton.

The sludge layer may sometimes be too heavy for a strong current of water to carry towards a filter. Some recirculating pond systems are still able to produce a large biomass of healthy fish in spite of it, and it simply grows as an undisturbed mound of waste until the entire pond is drained. More advanced ponds make use of a bottom drain to suck out the sludge periodically (though the drain itself can become clogged too). Medium-sized to smaller ponds may benefit from the use of a vacuum to suck out the sludge.

If the sludge is left behind and becomes disturbed, chunks of it can float to the surface and enter the pond pump. These chunks are usually too large and dense to be sucked through the filter, causing it to become clogged. You can also manually remove sludge with a net, but make sure your fish are transferred to a holding tank before doing so as it can be highly toxic.

4) Rear algae-eating fish

A pond loach
Having a few algae-eating fish in your pond, such as this pond loach, can effectively reduce algal populations. Manoel Jr., CC BY-SA 2.0, via Wikimedia Commons

Overproduction of algae can also clog up the pond filter, particularly when algal colonies have become large and thick enough to form mats on pond surfaces. Rearing a few algae-eating fish can effectively reduce algal populations and prevent the buildup of scum. Some popular ornamentals, such as koi, goldfish, and various plecos, tend to feed on algae in between feeding times. Other fish to consider include mollies and guppies, the Siamese algae eater (Crossocheilus oblongus), and pond loach (Misgurnus anguillicaudatus).

5) Pond biomass management

Fish food floating in a pond
You should remove uneaten fish food from your pond so that it doesn’t clog up your pump. shellac / CC BY 2.0

Pond planning and managing your stock density goes a long way in terms of sustaining a pond system. An overcrowded pond generates more waste than it can absorb without harming its inhabitants. It places heavy demands on pond filters, which can struggle to work efficiently if exclusively relied on to remove waste. A large amount of waste will likely settle on the pond bottom, as toxic sludge.

Moreover, overfeeding a large number of fish means double the waste! Uneaten feeds can enter the pump and eventually clog it. Always make sure to stock your pond conservatively, remove any uneaten fish food before they settle in the pond, and use high-quality fish feeds.

6) Proper winterizing

A frozen pond in a garden
Winterizing your pond is recommended before the first frosts occur. It includes things like adding beneficial bacteria that are adapted to cold weather and performing a routine water change. waferboard / CC BY 2.0

Ponds can accumulate a large amount of waste through the cold months. As temperatures begin to warm again in the succeeding year, you may be surprised by the amount of waste that has gotten trapped in your pond filter! Make sure your pond pump is in good shape and prepared for spring by winterizing your pond towards the end of each year.

This process is fairly simple and can be incorporated into routine pond maintenance sessions before the first frosts occur. Winterizing includes the following steps:

  • Prune or trim down plants with shoots that die back in winter. Those with root systems that won’t survive the cold should be treated as annuals or brought indoors. Cold-hardy marginal plants that require submersion should be snipped at their crowns and pushed deeper into the pond.
  • Remove any decaying leaves, twigs, fruits, and shoots on the pond bottom and surface.
  • You may seed the pond with a formulation of beneficial bacteria that are adapted to cold temperatures.
  • Clean the pond thoroughly and perform a routine water change. Algal film along the sides of the pond should be left untouched.

Cleaning & Unclogging Your Pond Pump

Bottles of Heinz white vinegar on a shelf
You can use white vinegar to remove residue in your pond pump, though it may ruin it over time. Mike Mozart / CC BY 2.0

If you have a skimmer or you frequently clean your pond, you will rarely have to pull out the pond pump, take it apart, and give it a good cleanse. That being said, residue will still build up in the pump over time, forming a film that can trap algae, bacteria, and small bits of organic matter. A great way to neutralize and remove the residue is with the use of citric acid. White vinegar should also be effective, but it may ruin the pump over time. Do check with the manufacturer beforehand as some pumps may easily corrode.

In terms of unclogging, your pump should come with a manual with steps on how to remove the volute cover and clean its interior chambers as every model can be slightly different. Remember to always unplug your pump from its power source before handling it, and make sure to reassemble it correctly before returning it to your pond. For a general guide, check out the video below for a overview of unclogging a pond pump so you get to know the main places to clean and what to look out for:

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