On Multi Bio Filter
The biological process of beneficial (nitrifying) bacteria assimilating nitrogenous waste is natural and occurs in the wild, as well as in your own pond. When your fish produces waste it eventually turns into ammonia, nitrites and nitrates.
If there is an improper biological filtration in your pond, it can leave your pond with an excess of these waste products which ultimately reaches a point of toxicity—killing your fish. Biological filtration is an aerobic process, meaning oxygen is involved.
Ammonia is broken down into nitrites. A second type aerobic bacteria will take the nitrites and break it down into nitrates. At low levels, nitrates are harmless to your fish but regular water changes are also a good idea (assuming the volume of water changed out is small enough that is doesn’t cause signigicant pH swings).
The name of the game when it comes to setting up your biological filtration is surface area. There are varying approaches to achieve high surface area filter media and these include porous rocks, ceramic rings, bio-balls and other plastic shapes that yield a high surface area. So why all the need for surface area?
A few beneficial bacteria assimilating your pond’s nitrogenous waste is good but a lot of bacteria is great so having a lot of surface area for these bacteria to live and thrive means that your biological filtration is that much more powerful.
For biological filtration, you want an oxygen rich environment so that the aerobic bacteria are able to assimilate the nitrogenous waste as efficiently as possible. To ensure this happens you need a pond with a large surface area and plenty of supplemental oxygenation via waterfalls, fountains, aquatic plants or diffusers.
When considering the right filtration system for your pond you will want to keep in mind that the entirety of your pond’s volume should be filtered every hour so choose a pump capacity/speed and filtration that will meet that goal. Let’s now take a look at some of the popular filtration systems to give you an idea of what’s out there and how they look when set up.