A biofilter is an integral part of any aquaponics setup because it helps beneficial bacteria to colonize. For this reason, the biofilter could be considered a necessity for aquaponics practitioners for them to obtain a profitable harvest.
As we all know, aquaponics is a recirculating farming method that combines aquaculture and hydroponics. Thus, it leads to raising fish and plants' growth in a symbiotic environment with beneficial bacteria. The process behind aquaponics converts fish waste into nitrates, which become plant food, and in exchange, plant roots filter and clean the water for the fish. A biofilter aids this process by ensuring that nothing is wasted.
What kind of waste is present in an aquaponics system?
The primary waste that is present in an aquaponics system is fish excrements. A fish emulsion made from plant waste is one of the most popular organic fertilizers, so it stands to reason that fish poop also benefits plants. When fish waste is used to feed plants, it provides naturally derived NPK nutrients and micronutrients.
How does a biofilter work in aquaponics?
The biofilter works by containing microorganisms that convert ammonia from fish waste into nitrates, which plants may use. Nitrification is a two-step process that accomplishes this.
The Nitrosomonas bacteria first convert ammonia to nitrates, which the Nitrobacter bacteria convert to nitrates.
The biofilter's environment should be bacteria-friendly. Content bacteria generate productive plants and happy fish, so the bacteria's living environment must be kept within specified parameters. The conversion of ammonia to nitrate only takes place in water with a pH of roughly 7.0 to 7.5. At this temperature, the nitrification process reaches its pinnacle.
The nitrification process, on the other hand, lowers the pH of the circulating water in the aquaponics system, necessitating the use of some form of pH regulation to keep the pH around 7.0.
The nitrification process slows considerably when the pH falls below 7.0. As a result of this situation, the following occurs:
- Ammonia is transformed into nitrates at a lower rate.
- There are fewer nutrients available for plants to grow.
- Ammonia poisoning can cause fish to perish.
How does biofilter help my aquaponics system?
If the surface area in your aquaponics grow media isn't adequate for the bacteria to colonize, you'll need to add more. This is why a biofilter is necessary. The biofilter is a crucial component of your system since it ensures that plants get enough nutrients to grow healthy while also purifying the water so the fish can live.
Here are some of the advantages of biofilters for aquaponics setups:
- It gives good bacteria additional surface area to thrive on and aids in converting ammonia and nitrites to nitrates.
- In NFT, DWC, and vertical aquaponics systems, the biofilter helps with aeration and nitrification.
- It helps your aquaponics system attain chemical stability.
What are the best biofilters for aquaponics?
Because the biofilter is not designed to handle numerous fish waste deposits that can become caught in the pipes, it must be installed after the mechanical filter. If this occurs, waste will continue to collect, forming an anaerobic zone that will encourage excessive bacteria growth away from the increased surface area that will not be used, lowering the biofilter's efficiency.
The mechanical filter serves as a screening filter, allowing the biofilter to cope with the build-up of solids.
Various models of biofilters are available for your aquaponics garden, but these three are the most common:
Moving Bed Filter
This biofiltration type, also known as a Moving Bed Biological Reactor (MBBR), is always in motion and rotates around K1 media with fixed aeration.
K1 media refer to small plastic discs suitable for catching suspended particles in water, and their vast surface area supports bacteria growth. Due to their near-neutral buoyancy ability, K1 media are subjected to a continual stream of air pressure that aerates the water, making them move around.
These flat-tray filters can be slid into a separate container that sits next to your tank, before the plants, and provide a large area for bacteria to collect on. In fact, you can choose your preferred density; the denser the media mat, the larger the surface area and the greater the number of nitrifying bacteria.
The third option is a filter that allows water to drip in from the top. It passes through a filter box filled with lava rocks, oyster shells or another bio medium with a large surface area. As the water slowly passes through this filter, the ammonia is converted to nitrates and ready to be pumped into your system's plant growing section. Again, this will need to be placed after the water has exited the tank, preferably after your solids filter, but before reaching the plants.
How long does it take for a biofilter to work?
Once the circulation in your aquaponic system has begun, you may need to obtain a starter solution. A starter solution is simply water from a previously established system containing bacteria. This significantly accelerates the cycling process.
The colonization of nitrifying bacteria in an aquaponic system to establish the nitrogen cycle is referred to as cycling. When ammonia is present, the bacteria required for colonization will begin to appear. This could take several months. However, by including the starter solution, the time will be reduced.
Once circulation begins, it is critical to maintaining the proper water pH and temperature to ensure that bacteria colonize the biofilter.