K1 Media – is it the best plastic media available?

What is K1 media?

K1 media by Evolution Aqua
K1 Media are small plastic wheel-shaped media with high surface area.

When it comes to selecting an effective biological medium it doesn’t get much better than K1 media. This can be used as an affective method of trapping suspended solids in a filter without the risk of blockage. But it is when K1 is used as a mobile biological bed that it really comes into its own.

With next to neutral buoyancy K1 media is easy to keep in constant motion with the use of air. By so doing it becomes self-cleaning with next to no maintenance. It also ensures that every part of the media has a constant flow of well-oxygenated water that is so essential for maximum breakdown of the fish ammonia.

K1 media was originally developed in Norway by  Kaldnes.   It was initially aimed at sewage treatment facilities, but it wasn’t long before the aquaculture industry became interested.  It’s use in pond filtration systems soon developed and companies like Evolution Aqua  started to include K1  in their range of koi filters. Evolution Aqua are now the world wide distributors.  

K1 media is a light, small, wheel shaped plastic media that floats easily. It is used in pond  filters to trap suspended solids and also to promote the growth of beneficial bacteria. These  micro-organisms convert toxic ammonia produced by the fish into less toxic nitrate, and ultimately nitrate, through the nitrification process. A key feature of this media is that it has a fantastic protected surface area which greatly aids the development of these bacteria. It allows bacteria to colonise within the filter and, at the same time, prevents the unnecessary loss of bacteria through excessive water movements.

In the centre of the wheel is a protected surface that allows the growth of a secure biofilm that is able to resist collisions when operated as a moving bed. 

Why is it important?

Maintaining excellent water quality lies at the heart of maintaining all aquatic life whether it is in an aquarium , garden pond on natural lake. It is often said that we are not keepers of fish but maintainers of water quality. When water quality deteriorates  the health of all aquatic life suffers and can lead to fish disease and, ultimately, an untimely death. 

How to use K1 and K1 micro

K1 media can be used in two fundamentally different ways.

1) As a static bed.

In this mode the filter is used mainly to trap suspended solids. These solids need to be completely removed from the pond, or fish tank, on a regular basis. This is easily achieved by expanding the media bed with air and running the resultant ‘soup’ to waste. The filter therefore should not be packed tightly with filter media.There should be at least 15% space available for the bed to expand.

2) As a mobile bed.

This is really when K1 and K1 micro comes into its own. The huge protected surface area of the media comes completely in contact with the waste and plenty of oxygen. The constant collisions prevent the accumulation of solids provided there is sufficient space for the media to become fully fluidised.

For the media to move it needs to be ‘conditioned’ in the filter for a few days in order for it to achieve neutral buoyancy. Initially it will float high in the filter and not flow easily. It’s only a matter of a day or two before everything operates in the way it should.

How much K1 media to use

It’s worth repeating that it is always better to underestimate the amount of media to include in a filter system. After all, having a larger filter does give a significant buffer capacity when the fish loads are higher than average, or the filter performance is lower than expected. Changes in feeding behaviour, stock levels and water conditions occur all the time and not always easy to predict. Fish keeping is seldom an exact science.

Nevertheless a crucial step in pond design is to correctly size the pond filter. Too large takes up valuable space and is expensive. Too small will almost certainly lead to poor water quality and a decline in the health of the fish. Very often manufacturers size their filters according to the size of the pond. This does not make any sense and will certainly lead to disappointment.

A better , and more scientific method, is to size the filter according to the maximum amount of fish food that it can be expected to purify. Fish food is the ultimate source of the majority of the pollutants that the filter is designed to control so this is a much more logical calculation. 

As a Rule of Thumb I would suggest that 1 litre of K1 media should be allowed for every 4g. of fish food. 

So, by way of an example, if you expect to feed a maximum of 200g. of fish food a day you should include 50 litres of K1 media. Remember this only a guide and is primarily used to size a filter before installation. once built and installed regular water quality monitoring is the correct method of assessing filter performance.

Alternative Filter Media

It is easy for nitrifying bacteria to colonise virtually any surface so there is a huge range of alternative media for this aspect of water purification. Similarly there is a large number of different media for trapping suspended solids. What defines all these media is primarily their abilities to be cleaned. Sooner or later they will all get clogged up and cease to be affective. 

The beauty of K1 media lies with its ability to be easily cleaned and resistant to clogging. Due to its neutral buoyancy a small amount of air injected into a filter will cause the bed to move, thus separating the excess solids from the media surface area. The solids can then be run to waste. In this way the effective surface area remains as high as possible.

Alternative Filter Media

It is easy for nitrifying bacteria to colonise virtually any surface so there is a huge range of alternative media for this aspect of water purification. Similarly there is a large number of different media for trapping suspended solids. What defines all these media is primarily their abilities to be cleaned. Sooner or later they will all get clogged up and cease to be affective. 

The beauty of K1 media lies with its ability to be easily cleaned and resistant to clogging. Due to its neutral buoyancy a small amount of air injected into a filter will cause the bed to move, thus separating the excess solids from the media surface area. The solids can then be run to waste. In this way the effective surface area remains as high as possible.

Recommendations

  • For all but the smallest aquaponic systems ensure you include a method of removing suspended solids
  • Solids should ideally be removed completely from the water on a regular basis, and not just trapped in a media bed where they will continue to use oxygen and produce further waste products.
  • Do not fill solid removal filters more than 80% to allow the bed to be expanded during the cleaning process,

Further Articles

  1. Fish ammonia 
  2. Fish poo
  3. The Nitrogen Cycle.

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