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Japanese Matting As An Excellent Koi Fish Pond Filter Bio-Media

The single biggest reason for the success of well designed vortex or other filters using Japanese matting is that large amounts of air pumped into the vortex biological chambers create highly significant turbulence which allows excellent mass transfer through maximising concentration differences as required and described above. This happens in conjunction with the simultaneous creation of large and open surface area structures on which many bacteria can thrive and grow - perfect conditions. Japanese Matting is successful not because of the matting per se but what the structure of the matting allows in conjunction with a vortex type filter design such as ...

  • Massive air injection through air stones before each matting section.

  • Very open structure of matting matrix

  • High flow rate large pump used

  • Although you cannot see it all solids have been efficiently removed to prevent clogging of the Japanese matting.

Only a small proportion of pond keepers can afford or really need large Japanese type matting vortex filters. However if you can afford it then it is one of the best ways without doubt and no matter what people say it has been proven time and time again. This is what a vortex filter looks like below they take up large amounts of space and are difficult to install on a DIY basis.

Vortex filter using Matlala Biomedia An USA company markets Matala (the invention of Marc Talloen who I first met in Germany) that is similar in performance and principle to Japanese matting.

If people try to convince you vortex filters are not highly effective you can be sure they do NOT really understand what is supposed to happen in a biofilter.

If You cannot afford or don't want to contemplate a vortex filter? On the assumption that second best has to do then all that has to be considered is

  • How do you get more surface area into your filter?

  • How do you get more turbulence?

  • How do you get more oxygen to the interface where the bacteria and the ammonia meet? and importantly

  • How do you get rid of solids accumulation, which is not good for your pond?

Look no further than modern pressurized pond filters by Hozelock, Oase and FishMate. My preference is for the FishMate for the simple reason it contains Alfagrog which in my opinion is the best low cost way to introduce more area into any conventional pond filter be it pressurized or otherwise ... throw away those hair curlers, plastic rings, onion bags and whatever else you might use. The use of Alfagrog in pressurized pond filters allows these filters to be extremely small relative to pond volume. This purpose built ceramic filter medium is coarse and full of interstices (small holes) allowing massive colonisation on large surface areas for all types of bacteria required in the biofiltration process.

Because of the high specific surface area (ie surface area per unit volume) which in the case of Alfagrog 40 amounts to a whopping 43 square metres per litre filters can be reduced in size which in turn allows higher levels of turbulence to be achieved or low residence times. Best of all it is low cost and is easily cleaned.

For comparison purposes 1 litre of Alfagrog 40 has the same specific surface area as about 100 litres of plastic tubes. It seems hard to believe but it is true.

But I Was Told The Pond Filter Must Be 1/3rd The Volume Of My Pond

When people say that the filter must be a specific ratio of the pond size then they are not considering the facts of the situation and are simply repeating what they have been told and do not understand the principles of biofiltration. Such advice is not based upon well-reasoned thought. Discard such advice is my recommendation. On the other hand it is impossible to have too large a filter. It just costs more money.

At this stage I have to say the following although I risk incurring the wrath of many people. However hopefully if you have followed my arguments so far you will undoubtedly agree with me.

Sand filters are bad for ponds but great for swimming pools and can only remotely be justified as solid removers. They perform little if any nitrification - poor surface area contact, low levels of turbulence, dead areas for pathogenic bacteria to accumulate, and low oxygen levels. I strongly believe there is no place for a sand filter in a pond environment. They are also extremely costly to run.

 If you have reached the stage where you believe you want to understand the whole process of pond filtration then go through these articles in the order presented.


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