Sludge is a natural form of decaying organic debris. Too much sludge can cause toxicity and cause problems with the ecosystem, so it is best to prevent the sludge from forming.
It's natural for sludge to develop at the bottom of the pond. It is made up of decaying organic materials, such as fish waste, plant debris, decaying algae, or dirt. A small amount of sludge in the pond is nothing to worry about. Your healthy bacteria and filtration processes should keep the sludge to a minimum and it won’t cause many problems in your pond.
You may experience problems if there is a lot of sludge at the bottom. In short, anaerobic bacteria develops in sludge and this produces hydrogen sulfide (an eggy or rottne smell); this is toxic and it can kill off your healthy bacteria and algae; this results in more sludge and creates a dangerous cycle. This can result in dead fish, plants, or wildlife.
Preventing Sludge: Physical Filtration
This method focuses on the traditional methods of filtration; but it also encourages prevention of sludge build up. A standard cover net can stop leaves or other debris from entering the pond, thereby stopping them from decaying. You can also use a skimmer net to remove floating debris and a sludge net to manually remove the sludge. While it may be time consuming, it can be rewarding; the sludge is high in ammonia, nitrites and nitrates; this makes it an excellent fertiliser for your garden plants!
You should also avoid overfeeding your fish, as left-over food can decay and cause sludge; a feeding ring can be useful to measure how much food your fish are eating. You should also be careful to prevent grass trimmings entering the water and trim dead or dying plants regularly to avoid these from decaying in the pond.
An efficient way of removing sludge involves an electric vacuum. The vacuum will suck up the dirty water and release the dirty water, allowing you to easily remove sludge and debris from the bottom of the pond. Don't worry about your fish either, they normally swim away from the vacuum.
Long Term Prevention (Useful Blogs: Water Quality, Filters & Their Maintenance)
You should also invest in an appropriate pump and filter system; this will remove the sludge without much effort. Most filters also come with UV and biological filtration, which helps to improve water quality and clarity. In short, a solids-handling pump pushes water from your pond to a filter that sits outside of the pond. The filter's foams will collect the debris and remove it from the water, thereby stopping the sludge from causing harm to your pond.
Filters normally contain a UV bulb and biomedia. The UV bulb will help to sterilise algae in the pond, which stops the water from turning green. The biomedia (small plastic balls at the bottom of your filter) is where healthy bacteria develops; this bacteria breaks down Ammonia, Nitrites and Nitrates to maintain healthy water for your fish.
Preventing Sludge: Biological Activity (Useful Blogs: Aeration, Bacteria: The Importance of Healthy Bacteria)
A natural way to encourage healthy bacteria is to aerate your pond. You can add air through a variety of methods (an air pump, fountains, and waterfalls) and the aeration will improve water quality, reduce algae growth and odours, improve the fish environment, reduce diseases, and assist in the breakdown of sludge through healthy bacteria. Making sure your pond is properly aerated is one of the top 5 things we always recommend for a pond; this is because the results are impressive.
If you already have an aerator and you would like to add extra bacteria, the PondXpert Gel Balls can be used to release healthy bacteria and enzymes, which balances the chemicals in the water while also treating ammonia and nitrite issues.
Treating Sludge: Chemical Treatments
The two above methods help to prevent sludge; but if you have already developed a sludge problem, it is likely you will need to treat the water with a chemical treatment. The PondXpert Sludge Eliminator is a popular choice, as it is a blend of natural organisms and minerals which help to remove sludge.
If you need any further assistance or if you are experiencing problems with sludge, please email us on info@pondkeeper.co.uk.