Comparing Different Pond Filter Biomedia
Bacteria in fish ponds grow on the pond filter biomedia surfaces ... More surface = more bacteria = cleaner pond water
The more bacteria you have in any pond filter the better your pond water quality will be. These filter bacteria transform toxic chemicals in the pond water secreted by the fish into plant fertilizer suitable for pond plants. Choosing the correct biomedia has a major impact upon your pond filter's performance
A pond filter will do a good job if there is a way removing solids effectively and of colonising large surface areas of filter bacteria that are able to intimately contact the water containing the waste products pumped through the system and if there is continuous flow of oxygenated water through the biofilter we tend to use the word filter as a short version of biofilter.
Click here to learn how a biofilter works.
The more surface area that can be incorporated into a filter the better. An attempt (albeit a basic attempt) to achieve this is by placing hollow tubes of rough plastic inside the filter box. Other attempts include the use of orange bags, lava rock, tubes, and even hair curlers.
Typical tube appearance used as biomedia
Certainly all of these methods create holding areas for the bacteria but they are all inefficient and therefore large sized boxes are required to create sufficient area for the bacteria colonies to grow on. The generic term for all these substrates used for holding bacteria is BIOMEDIA - a medium to hold pond filter bacteria.
| UV + Bio Pond Filter Selection Table ... By clicking the link below you can review a wide range of biofilters both with and without UV sterilizers. | ||
Fish-Mate Includes UV Sterilizer (see below ... if you're looking for a low cost well tested UV + filter combo for a small to medium fish pond this would be my recommendation) |
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| UV + Biofilter for ponds to 1,000 gallons | UV + Biofilter for ponds to 2,000 gallons | UV + Biofilter for ponds to 3,000 gallons |
| Combo UV + Biofilter for ponds to 4,000 gallons | UV + Biofilter for ponds to 5,000 gallons | UV + Biofilter for ponds to 6,000 gallons |
Foam sheets by virtue of the many small holes in them also provide surface on which pond filter bacteria can grow as well as acting as a mechanical filter to remove solids.
Here is an example of what could be used as a low efficiency medium. It does look nice. It would be about as good as hair curlers or plastic tubes in effectiveness.
By far the best means of getting large surface area and thus large quantities of pond filter bacteria into a small black box biofilter at low cost is to use porous ceramic materials like Alfagrog. This is a product made in the UK specifically for fish pond water purification. It has a massive surface area of between 40 and 100 sq. metres per litre depending upon the particle size compared to 0.2 square metres per litre for plastic tubes. Look at the chart below:
Without getting too technical this means that 1 litre of Alfagrog can hold the same amount of pond filter bacteria as 200 litres of plastic tubes. In other words a box using plastic tubes needs to be 200 times bigger in volume than one containing Alfagrog to get the same biological performance.
Alfagrog looks a bit like cinders, it is lightweight, comes in different sizes and you can literally blow through it because it is so porous.
Here's a picture showing a typical box filter (sketch by Peter J May)
You can build your own filter.
Buy low cost combo biofilters and UV units containing the best biomedia, Alfagrog, by clicking this image Combo filter & UV
"The Complete Pond Solver" by Tony Roocroft
2005 Edition. Essential reading for anybody who wants or has a garden pond. Get 12 Excel pond calculators free as well as "Water Lilies and Pond Aquatics" ebook also free