Types of Pond Filter Media and How they are Used
Author: Terry Newhaven
There are different types of pond filter media available for use. All of these options are natural, efficient and cheap to boot. While they can't replace a good filtration setup, each option can be added to further streamline the pond and make filtration easier on both you and your filtration system.
Activated carbon (AC) is a natural material that comes from various sources like bituminous coal, lignite, wood, coconut shell, etc. It is activated by steam and other means and each source of activated carbon has different adsorption properties. Activated carbon is a very efficient material. One pound of carbon contains a surface area of roughly 125 acres and can absorb literally thousands of different chemicals because of its slight electro-positive charge, making it even more attractive to chemicals and impurities. As the water passes over the positively charged carbon surface, the negative ions of the contaminants are drawn to the surface of the carbon granules, making it easier to filter impurities out of your pond. The more carbon activated, the better. This type of filter media works best in ponds with low flow rate because it gives the contaminates more time to be in contact with the carbon in order to get better absorbed.
Bio-balls provide an excellent substrate to grow beneficial bacteria in a pond. They also produce turbulence, which helps with the gas exchange process in that it converts toxins or eliminates them altogether. Bio-balls increase the surface area for beneficial bacteria for both housing and growing colonies of bacteria that consume ammonia and nitrite, two chemicals that aid algae growth. They are easy to use as well. Just add them directly to your biological filter and let the bio-balls increase your system's efficiency. Bio-balls offer an efficient and cheap way to keep your pond clear and create a healthy natural system.
Zeolites are natural minerals that exchange one charged ion present in their crystalline structure, for another one present in the surrounding media. They have very rigid structures that allow water to flow through and still attract and catch impurities. Zeolites remove ammonia, provide a large surface area for nitrifying bacteria, and keep your water biologically clean and clear. Zeolites are used in water filtration processes to absorb toxins and heavy metals found in hard water, remove micro particles in the water and reduce algae growth. The best thing about this sand-like mineral is that it is non-toxic and naturally occurring, making it safe for plants and fish, further enhancing the overall health of you pond. Zeolite can also be re-used by giving them a simple saltwater bath. The saltwater causes the trapped ammonia to be released. Be sure to rinse the zeolite off in freshwater prior to placing back into the filter.
Foam sponge filters are a simple and cost-efficient way to trap debris mechanically. Sponge filters work by drawing water through the porous sponge and trapping debris and allowing beneficial bacteria to remove wastes like nitrites and ammonia. Water is pushed through the sponge by the pond pump connected to the filter. Foam sponge filters are also efficient biological filters in that they are porous and can maintain large bacterial colonies in proportion to the space they occupy. They are cost-effective due to their simple design and low-cost materials. They can easily be used in ponds by attaching a power head pump and running the return line back to your pond or waterfall.
Ceramic rings can be less economical in large quantities in other filter media, but they provide the most surface area and won't break down over time. They work about the same way as bio-balls in that they are highly porous and still rigid enough to both allow water to flow through as well as catch impurities. Ceramic rings are chemically inert, versatile and nearly indestructible.
Biological filter mats are made from curled polyester fiber and coated with a water resistant binder that allows bacteria to attach to its large surface area. Filter mats sink hold nitrifying bacteria that change ammonia and nitrites into nitrates and are porous to allow water to flow through it without clogging. Filter mats are rigid and are easy to handle and clean and are designed for years of use.
In summary, the different types of pond filter media accomplish one of three things: trap pond debris, provide a substrate for bacteria colonization, or directly remove toxins and impurities. Some provide a combination of 2 or 3 of those functions, other just one. All of these are ecologically sound options designed for long term use to create a well-balanced pond with a natural appearance.