A biofilter is only as good as the biomedia used. Many models of biofilter can be made to perform better by replacing the cheap filter media, usually plastic coils with a superior pond filter media with a higher SSA (specific surface area). Pond filter media selection is critical to pond keeping success but is sadly over looked or not known about. This article is an attempt at trying to convince the uninitiated ....
A biofilter converts ammonia in fish ponds into nitrates which are much less harmful than toxic ammonia. The process is known as the nitrogen cycle and is the sole purpose of pond filter media. In pond keeping terms and more specifically in pond filter media terms "bigger is not always better". I will explain ...
When choosing a garden pond filter look at the pond filter media included and choose a pond filter model with as high a SSA as possible. A smaller filter model with a superior pond filter media will perform as well as a large filter model using an inferior filter media, such as thin plastic coils.
Example:
You have decided to use a thin plastic coil that measure 2in high x 1in diameter.
Formula: 2 x pi x plastic coil diameter x plastic coil height.
Area for bacteria to colonize = 2 x 22/7 x 1/12 x 2/12 = 0.1 square feet.
So for arguments sake we shall assume that your pond needs 1000 million bacteria and 0.1 sq feet can provide space for 1 million bacteria. Also for effective filtration we shall assume that your pond filter requires 1000 plastic coils inside it.
The volume of 1 plastic coil is approx 0.0012 cubic feet. This means that your pond filter would need a total volume of 1.2 cubic feet to house 1000 plastic coils.
If you decided to double the weight of fish in your garden pond then you would need 2000 plastic coils. This would mean that you need a filter box with a volume of 5 cubic feet.
The key is to find a pond filter media with a higher SSA than platic coils. If you were to use a filter media that is the same size but has 40 times the SSA then the filter box can be 40 times smaller and you will only need 1/40th the number of plastic coils to house the 1000 million beneficial bacteria.
What is the Best Filter Media?
Any biological pond filter media that is capable of removing solids effectively and of housing large colonies of Nitrosomonas and Nitrobacter bacteria will be a good choice. The larger the SSA (specific surface area) of the biofilter media, the better, as it will significantly improve pond filter performance and remove ammonia from your garden pond at a quicker rate.
The full article can be read at http://www.garden-pond-filters.com/garden-pond-biomedia-article.html, where you will find other interesting articles and product resources.
