Biofilters

How To Choose Pond Bio Filters For Clean Healthy Pond Water… Look For Alfagrog Biomedia in Filters For Fish Ponds. All fish ponds need a bio filter to allow water in which fish live to remain clean and healthy. Pond fish pollute their own living space and we must help them clean it to prevent the goldfish or koi from dying.

What is a biofilter, and why Alfagrog biomedium?

Alfagrog should be your biomedia choice inside your fish pond filters. Fish pond filters purify pond water at the interface with the biomedia. This is where the bacteria colonies reside and do their biofilter work. The better the biomedia the smaller homemade pond filters can be. You can improve the performance of any biofilter containing foam or plastic shapes (eg cylinders or balls) by adding Alfagrog to the filter. By doing this there is no need to increase the size of your filter if it is underperforming or not coping as your fish get bigger.

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View our range of Biofilters and Alfagrog here.

Alfagrog compared to Ceramic Rings, Lava Rock, Plastic Foam, Plastic Coils. Table shows SSA in sq.m. per litre for different biomedia used in home made and commercial pond filters – build your own pond filter.

Biofilter Needs Alfagrog

All biomedia in fish pondfilters or biofilters of any type can be classified according to its specific surface area (SSA). The higher the SSA the more probable is it that the biomedia will be more effective in fish pond filters. SSA means how much surface area per unit volume of a type of media is available for colonisation by bacteria inside fish pond filters. You can now see how you can easily choose biomedia for your diy pond filter.

As can be seen Alfagrog has 45 sq metres per litre and plastic coils only 1 sq metre per litre. For products like simple plastic tubes inside a diy pond filter SSA can be calculated easily because it is a smooth surface and a simple shape. In fact if you do the calculation the SSA is about 1 sq metre per litre of biomedia. In other words if fish pond filters are filled with plastic tubes then for every litre used about 1 sq. metre of surface is provided for colonisation by the bacteria.

For any fish pond the amount of bacteria required to keep water clean and healthy is determined by:

The amount of ammonia released within the pond due to food (fish stocking and feeding rate). The availability of oxygen in sufficient quantity for the bacteria to do their job efficiently and The number of bacteria in the fish pond filter which is related to the SSA.

Therefore for any pond lots of SSA inside a fish pond filter must be better. I hope you agree.

This has a practical and significant cost implication. It is the biomedia SSA used together with flow rates and oxygen concentrations that determines the size of pond filters or biofilters boxes and NOT the size of the pond. To this date I have never met a retailer who really knows this let alone uses the principle.

Most retailers sell big boxes for big ponds and small boxes for small ponds.

Even so called “koi experts” talk about the size of pond filters in terms of pond size or even its surface area as I saw in one “expert” publication recently. This is nonsense and has caused so many people to build totally inappropriate fish pond filters over the years.

In practice a small fish pond filter box is perfectly adequate for a big pond so long as the biomedia is selected carefully and the outlet from the box is big enough to allow the water to flow out under gravity.

This knowledge can save you many Rands and even if you have spent your money already it will give your existing homemade pondfilters or any other fish pond filter or biofilter a big boost in performance. The media I recommend is very low cost and is perfect. I have used and sold it for use in all types of fish pondfilters many years.

The terms uv pond filters, uv filters for ponds and uv filters for water gardens are terms you will frequently come across. They are related to the use of ultra violet light and not biofiltration

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