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05 October 2017
What are the different types of filtration?

What are the different types of filtration?

Filtration is the process by which your pond is cleaned of impurities.  With modern filters there are three major stages:

•  Ultra-Violet Clarifier (UVC)

The UVC subjects the pond water to UV radiation.  This means that microscopic single-cell algae flocculate (stick together).  The resultant large particle pieces are picked up by filter foams and prevented from re-entering the pond.  This prevents your pond looking green (like pea soup).

•  Mechanical Filtration

Pond debris such as fish waste and dead pond plant particles are caught in mechanical barriers – typically foam.  These foams are often graduated to catch even the smallest pieces.

•  Biological Filtration

Finally pond water will often pass through a bed of bio-media.  This material is designed to maximise their surface area which allows friendly bacteria grow on them.  These bacteria will break down Ammonia, which is caused by dead and decaying organic matter, into Nitrite.  A different type of bacteria then breaks this dangerous Nitrite down to Nitrate and will be absorbed by plants as they grow.

What is a Gravity Filter?

The water flows through these filters slowly as they are not a sealed unit.  This means that they provide a better level of filtration as the dirt has more time to sediment out.

 The draw back of this is that they can not be sighted away from the edge of the pond as any extra pipe work on the filter can cause the water to back up and overflow the top of the unit.

 These filters are ideal for those wanting to dabble in keeping Koi


What is a Pressurised Filter?

The water flows through these filters much more quickly as they are sealed units and thus maintain the pumps pressure.  This means that they do not provide a great level of filtration as the water spends less time inside them and there is not chance for the dirt to sediment out (sink to the bottom).


The major benefit of this is that they can be sighted away from the edge of the pond with extra hose bringing the water discretely back to the pond.  They can also be sighted below the level of the pond as the water maintains its pressure.

 These filters are ideal for those wanting to keep clear water but do not want to spend the time or money on a flow through box, as well as wanting to hide it away.


Can I filter my very large pond?

Large Ponds / Lakes

The liners we do will allow a body of water from 20 Litres all the way up to 999,000 Litres.  The largest filter we do is the OaseBiosys Sets.  These will cope with a pond of up to about 70,000 Litres.  This leaves another 929,000 to be treated, or does it......?


Ponds < 100,000 Litres

For ponds up to approximately 100,000 litres it is still possible to treat the water appropriately and provide relatively  clean water.  This can be done via a combination of separate pump and filter sets For example a 90,000 Litre Goldfish pond should be kept relatively clean by running 2x Fishmate Pressurised  45,000 Filters each with a 22,000 Pump.  The bigger the pond the more appropriate a box filter is, which would mean you could instead go for two of the Oasis Green2Cleans or Clear Ponds.  So long as the aim of turning the water over once between 1 and 2 hours is met then clean water is still a possibility.  It is often cheaper, and if installed properly more effective, to get two pump and filter sets than to have a bigger single pump and filter system.


Ponds > 100,000 Litres

 Once the size gets much above 100,000 litres there is very little need to filter it further.  To get crystal water will become harder and harder, but the actual quality of the water will be absolutely fine.  So long as there is a flow of water through the pond then the natural biology and ecosystem of the pond will look after the water quality itself.


Do all ponds need a filtration system?

The simple answer is No.  If you are not intending to keep fish in the pond and therefore a natural wildlife pond, there is no need for a filter to be used or even a pump as the type of wildlife that will be attracted to this type of pond such as frogs prefer a boggy type of area.

What can a filter system add to my pond?

If you are looking to create a natural wildlife pond, then a pump and filter will not be required as the type of wildlife that will be attracted to this type of pond such as frogs prefer a more bog like area to live in.

A pump will provide movement of the pond water and a filter will enable the removal of algae and dirt, whilst restoring the ponds balance through the addition of 'good' bacteria from a matured filter.  Installing a pump in the pond can allow for the creation of a fountain or waterfall; along with a feed to a filter system.

This is an essential part of pond keeping and is explained more thoroughly in the fish section. 

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