About fish pond filters

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For every pond that has been set up there has to be a filtration system incorporated into the design to keep the water fresh and free from harmful contaminants. There are many too choose from on the market and all different sizes to suit different ponds. Indeed, many pond keepers have become skilled enough to make their own filters. Hopefully by answering the following questions, it should be clear which filters are required and why they are necessary.

Do I need a pond filter and what methods does it use?

The answer to this question is “yes” if you are planning to keep fish you need a filter with no exceptions to run a successful pond. If you are looking at a natural wildlife pond, then sometimes it is not required. The plant life in the pond will soak up any nitrates present in the water.

As well as filtering the water mechanically (particles are removed as they pass through a set of sponges), it also converts any ammonia that is created by fish waste and rotting vegetation into nitrates by hosting beneficial bacteria that do the work.

How do I know which size filter I need for my pond?

The size of the filter required is rated by the size of the pond. Any filter used should be capable of turning over the total water volume of your pond every 1 to 2 hours. It is virtually impossible to over filter your pond, especially if your stocking level is high. So if you have a pond that contains 500 litres, your filter should be capable of turning over at least 500 litres per hour. If the pond has a few fish with lots of plants then a 500 litre pond will probably only need a filter that is capable or turning over 300 litres per hour.

What types of filters are available?

There are basically three main types of filter available for ponds.

• Gravity return filters
  The set up in these requires a pump that feeds the water from the pond up to the filter and then the water is returned by means of gravity. The only drawback with these is the fact that the filter needs to be higher than the water level of the pond for it to work efficiently.
• Pressure filters
  These are ideal for the smaller ponds as the water is fed into the filter via a pump and leaves the filter under pressure as the filter is a sealed unit. These take up less space and can be positioned anywhere.
• Gravity fed filters
  The gravity fed filter is often used in large Koi ponds, the water is fed to the filter by means of drains in the bottom of the pond and then pumped back into the pond afterwards. These are very complex and usually fitted by experts.

What is a mechanical filter?

A mechanical filter is purely used for removing particles and debris from the water. The filter will contain varying grades of sponges to perform this task. These are sometimes used in very small ponds and do not take up a lot of space.

How do I set up the pond filter?

With any bought pond filter there will be a pump that will feed the filter, this needs to be placed below the water surface at all times. By the means of piping this will be connected to the filter inlet. The filter box needs to be placed at the side of the pond; with some models they can be submerged in the ground to hide them. If the filter is a gravity return, remember it needs to be higher than the water level of the pond. The water is then returned to the pond by more piping.

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Fish pond pump

How will I know if the pump is too strong for the size of my pond?

Any pump will have its rating on the packaging, or even on the pump itself. The rating will be displayed in litres or gallons per hour. The filter that is being used with the pump should also display a rating the same, if both pump and filter match the same rating, there will be no problem.

Why isn’t my pond filter working properly?

Normally the filter will stop working when there is a blockage, this is normally inside the filter as the sponges get clogged with debris. In the summer months when the filter is running 24/7 checks should be made on a regular basis to make sure the filter is working fine. If the sponges are blocked, rinse them out in old pond water- never use tap water to do this.

Check the piping for a blockage, the use of stiff wires pushed down the pipes will move any debris that is jammed.

If the filter is clear and the piping isn’t blocked then it has to be the pump that has broken down. There is only one action to take in this scenario, buy a replacement.

Is my fountain acting as a filter?

This depends on the fountain; certain models will have a small sponge filter built into them but not all models. The main uses for a fountain are for display reasons and to keep the water well oxygenated.

What is a natural water filter in a pond?

This is where a mini ecosystem is created in the pond and the balance of the pond is as near perfect as possible. This will take a lot longer to run properly and a lot harder to get right. Lots of plants are added to the pond; at least 2/3 of the pond will be planted. The plants will then act as the filter along with any bacteria in the water, soaking up any toxins in the pond that are produced by fish waste or rotting debris.

If my water gets polluted how do I clear it?

If the pond water is polluted from outside sources by chemicals or like wise, act quickly to remove it. Large water changes should be performed and add a commercial filter carbon into the filtration system to soak up any toxins. Once the toxins have been absorbed, remove the carbon and perform another water change.

Can I make my own pond filter?

It is quite an easy task to build your own filter without too much hassle. Basically a filter is a box with separate chambers for the media. Keeping this in mind all you need is two chambers that can be converted rain barrels, old dustbins, and plastic storage boxes, whatever you have in hand. In the first chamber place some sponges or brushes to act as debris catchers for the mechanical filtration, and in the second chamber add some bio balls or lava rock to perform the biological filtration. Drill the sides of the chambers and join together with piping, add piping to the side of the first chamber to connect the pump to. Add piping to the side of the second chamber to add return piping and you now have a complete filter.

Will a filter net prevent large debris blocking the filter system?

This is exactly what the nets are for. On a regular basis gather up debris from the surface of the water, some of the larger particles will clog your filter if they reach it. This is particularly important in the autumn as leaves fall from the trees and any shrubbery around the pond cast their foliage. Covering the pond with a purpose made net will also prevent a lot of the debris falling into the pond.

Is there a kit available to set up a small pond?

There are various kits available that contain all you need for setting up a small pond. It will contain the filter, pump and in some cases the liner that is used to create the pond. Often this is the cheapest way of setting up as everything is rated to the size of the pond and if purchased as one unit a discount is given. Prices do vary a lot between the suppliers so shop around for the best bargain.

About fish pond filters

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