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What Is An Aquaponics Biofilter?
Many aquaponics beginners are often confused by the need for filtration in their aquaponics system. Do I need to add a biofilter? It is one of the frequently asked questions in aquaponics. To answer the question, we wrote this article to discuss biofilter, what it is, and do you need to have one in your aquaponics system.
The idea behind aquaponics is that it is possible to imitate nature to create a perfect growing environment for the fish and plants to grow. Aquaponics is a recirculating method of farming that combines aquaculture and hydroponics, leading to the raising of fish and growing plants together in a symbiotic environment with beneficial bacteria. It converts wastes produced by the fish into nitrates, which become plants' food, and in return, the plant roots filter and clean the water for the fish. A biofilter helps this process to ensure that nothing goes to wastes.
What Is A Biofilter
A biofilter is a place for the bacteria to colonize. It provides large surface areas, pH, dissolved oxygen levels, and proper temperature.
Biofilters are quite simple to set up, and they consist of a tank connected to the air pump and some substrates that provide as much as possible a big surface area for the nitrifying bacteria to grow. The more surface area for the bacteria to develop, the better because it means a more efficient nitrification process.
What Is Biofiltration
Biofiltration is the conversion of ammonia and nitrite into nitrates by the beneficial bacteria. Ammonia and nitrites are toxic to aquaponics, even at low concentrations. However, plants need the nitrates to grow, so a biofilter needs to be installed to house most living bacteria. The water movement within a biofilter will break down the very fine solids not captured by the clarifier which prevents a waste build up on the plant roots in the NFT aquaponics system. Good biofiltration is also essential for the chemical stability of your aquaponics system. Separate biofilters are unnecessary for the media-based aquaponics system because the grow beds themselves are perfect biofilters.
Why Do You Need A Biofilter
In aquaponics, if the surface area in your grow media is not enough for the bacteria to colonize, you need to add more surface area. This is why you need to have a biofilter. The biofilter will form an important part of your system by ensuring that plants have enough nutrients to grow healthy while cleaning the water for the fish to live.
Your whole aquaponics system is a biofilter. However, if you are using the DWC, Vertical, and NFT aquaponics system to grow your plants, you will need a biofilter. In these types of aquaponics systems, you can't rely on the natural process of bacterial conversion because of a lack of adequate surface area. A media-based or raft aquaponics system does not usually need a separate biofilter because the raft, growing media (expanded clays, gravel, or lava rock), tank walls, and other surface areas provide enough area for the bacteria to colonize.
Benefits Of Using Biofilter In Aquaponics
1. It provides more surface area for the beneficial bacteria to live and helps convert ammonia and nitrites into nitrates.
2. Biofilter assists in aeration and nitrification processes in the NFT, DWC, and Vertical aquaponics systems.
3. Aid in the chemical stability of your aquaponics system.
4. Very inexpensive and easy to build.
5. Very easy to use and require very little maintenance.
Important Factors To Consider Before Using A Biofilter
Before you decide to use biofilter in your aquaponics system, you must be aware of these considerations.
- Remove The Solids First
Biofilters are not for large solid fish wastes. Solids must be screened because this will possibly block the pipes. Once these solids accumulate in your biofilter, this will create areas known as aerobic zones that will attract bacteria and reduce your biofilter's surface area. This will reduce your biofilter's efficiency, which will result in a high ammonia level, which is not suitable for fish and plants. That is why it is important that you add a standard filter that will remove the solid.
- Bacteria Needs Air
In an aquaponics system, the bacteria are exposed to the air. Adding a biofilter in your aquaponics system will contain the bacteria in the filter. So you have to make sure that your filter has enough air supply to ensure that the bacteria is not deprived of air.
- Fish Density
If you are running a low fish density, then you don't need a biofilter. Low quantities of fish will not produce enough waste to justify the use of a biofilter. The plant's roots will provide enough surface area for the bacteria to convert ammonia into nitrates.
How Does Aquaponics Biofilters Work?
The biofilter is the extension of the surface area of your aquaponics system. It is an essential part of your aquaponics system because it ensures that your plants can access the nitrates that they need to grow while cleaning the water for the fish. The bacteria will attach to the surface of your biofilter media. Once they are established, they do their job and help convert ammonia and nitrites into nitrates.
Biofiltration in aquaponics happens in three main steps:
1. The air pump pumps the water out of the fish tank and into the biofilter.
2. Inside the biofilter, the water goes through the nitrification process. The beneficial bacteria help convert ammonia and nitrites into nitrates.
3. The water full of nutrients flows out of the biofilter and into the plants, where the plant roots absorb the nutrients while cleaning the water before it goes back into the fish tank.
This process is for typical aquaponics set up. The process or steps may vary depending on your biofilter design.
Different Kinds Of Biofilter
There are several aquaponics biofilters that you can use in your aquaponics system; these are:
- Moving Bed Filter
This biofilter is used in a floating raft system where there is not much surface area for the bacteria.
These are tray-like filters that can be slid into a separate container next to the fish tank before the plants. These provide a large area for the bacteria to collect on. This filter needs to be positioned after the solid filter before it reaches the plants, allowing the water to be filtered before it reaches the plants.
- Drip Filter
This filter allows water to drop in from the top. The water passes through the filter box, full of gravel, oyster shells, or another similar bio medium with lots of surface area. This biofilter also needs to be positioned where the water is filtered before it gets to the plants. As the water moves through the filter, the ammonia is converted to nitrates before it is pumped back to the plants.
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