There are many different configurations of Aquaponic systems. The components common to every Aquaponic system are the fish tank and a plant bed. The variables include filtration components, plumbing components, the type of plant bed and the amount and frequency of water circulation and aeration. Generally speaking, systems that utilize some filtration to remove the solid fish waste will have higher production of fish and plants than those that don’t use filtration.
There are three primary Aquaponic methods emerging in the industry. Each if these methods is based on a hydroponic system design, with accommodations for fish and filtration.
NFT is commonly used in hydroponic method, but is not as common in Aquaponic systems. It is a method that uses PVC pipes or enclosed gutters with the holes and plants set in them. In NFT method, nutrient-rich water is pumped down to the pipes only in a very thin film just enough to hit roots. Plants sit in small plastic cups allowing their roots to access the water and absorb the nutrients.
NFT is suitable for certain types of plants, generally leafy green vegetables.It is important to filter the Aquaponics fish tank water before sending it through NFT pipes, otherwise the fish poo and uneaten fish feed tends to clump up in the pipes and among the plant roots causing anaerobic, smelly conditions that are not very good for the plants, fish or relations with neighbors.
- You can have a large amount of plants in a small area.
- Requires less fish.
- Can be very productive.
Disadvantages of NFT Aquaponics
- All solids must be removed by filter or solid separator as the solids will tend to cling to plant roots and drown them and/or clog system.
- Bio filtration must be used as there is usually not enough surface area for beneficial bacteria to break down the ammonia to nitrogen.
- There is not as large a volume of water, making system susceptible to temperature and PH swings.
- Mineralizers may be needed to utilize the minerals from the solids that are separated.
- Generally not considered a good choice for Aquaponics due to these problems. (better suited for hydropnics).
>>> Raft or Deep Water Culture
In the raft Aquaponics system, the oxygenated water is continuously flowing through the system and the plants are floating ( usually in net pots filled with perlite, hydroton or rockwool suspended from Styrofoam floating in the water). Deep water culture also called raft Aquaponics system was borrowed from hydroponics and modified slightly for Aquaponics. Deep water culture works well with Aquaponics because the large volume of water needed tends to keep the PH and temperature stable. This is good for both fish and plants.
One difference from the hydroponics system is that the water should be filtered to get out the solids, this can be done with a simple clarifier or filter. Solids allowed to stay in this type of system can coat the roots and not allow them to get nutrients, or worse yet drown the plants. Of course one advantage over hydroponics is that once a system is established the water is always recirculated and never needs to be dumped as in hydroponics. This method is one of the more commonly practiced commercial methods.
Advantages of Raft Aquaponics
- There is plenty of surface for the beneficial bacteria to grow
- Tends to be very productive yielding a lot of plants
- Very good for lettuces and leafy vegetables. Used extensively by commercial farmers.
- The large volume of water involved tends to make keeping the water temperature and PH balance more stable.
Disadvantages of Raft Aquaponics
- Requires additional filtration to remove solids
- Large plants such as tomatoes, cucumbers etc. can be difficult if not impossible to support.
>>> Media-Based Method.
Media filled beds are the simplest form of Aquaponics where grow bed is filled with medium like expanded clay balls or hydroton, pebbles or gravels. Water from a fish tank is pumped over the media filled beds, and plants grow in the rock media. This style of system can be run two different ways, with a continuous flow of water over the rocks, or by flooding and draining the grow bed, in a flood and drain or ebb and flow cycle.
- No extra filtration is required, all of the solids are used in the grow bed.
- All the nutrients from the fish waste are used, therefore no mineralizers are needed.
- You can grow just about anything in this type of system.
Disadvantages of Media-Based Aquaponics
- With time the system can become clogged and will need to be cleaned.