3. • The Aquarium Aquaponics System
or
A Nano Aquaponics System
• Here is introducing a hobby-size DO-IT-YOURSELF fun project for you and the kids. You can convert any aquarium to an aquaponics
system in this way and grow some food or flowers indoors.
• Please make a note of a few things:
1. The pictured grow trays are good for most all greens and herbs used in daily cooking but flowering/fruiting large plant roots
would clog the system quickly.
2. Do not ask me how many fish you can add in this system. Use very low density ornamental fish load instead.
3. This system is not properly sized and is unbalanced. Hence do not expect a consistent growth and output by the plants.
Disclaimer: copy and do this at your own peril.
4. You will need to change your fish feed and use a more balanced diet for the fish so that plants get proper nutrients.
• Components as you see it in the system are as follows,
1. Aquarium fish tank
2. Biofilter trays on a stand filled with sand as media
3. A circulation pump set on a timer and needed plumbing
4. An air pump for redundancy. We used cascading water aeration from the drain holes using a geo-membrane liner placed
underneath the biofilters.
5. Your favorite fish and plants.
4. Media Base Bed
• Media-based aquaponic systems, also known as media bed or gravel-bed systems, use a rooting medium like perlite, clay balls, gravel, or river rocks,
on which plants are grown. This porous growing bed provides ample spaces for the growth of beneficial, nitrifying bacteria, and also allows for the
cultivation of larger flowering and fruiting plants like tomatoes or cucumbers, as compared to NFT or Raft systems. Depending on the arrangement,
water may flow at a constant rate through the bed, or the bed may be flooded at times, and dry at others. While the plant roots take up all the
nutrients from the water, the gravel bed also has a filtering action, which makes a separate filtration unit unnecessary. Purified water is then routed
back to the tank.
• Pros
•
- Simple system and relatively inexpensive.
- Similar to ordinary gardening, because the media bed resembles a regular soil bed.
- Suitable for all kinds of plants, from leafy greens to larger fruiting ones.
- The medium performs a filtering action, preventing debris from returning to the tank.
- Trapped waste gradually reaches tray bottom, in a thorough purification process.
- Air is present between medium particles, supplying oxygen to the roots.
- Red worms can be added to the gravel bed for further breakdown of waste.
- Suitable for hobby applications and home gardens.
• Cons
- A good-quality medium can be somewhat expensive.
- Over time, the pore spaces in the medium may get clogged, causing anaerobic conditions that are bad for plants.
- Regular cleanup of growing bed is required.
- Some types of rooting media may change the pH of the water.
- Not suitable for commercial purposes due to lower productivity, labor intensiveness, and difficulty in large-scale implementation.
- Gravel beds are heavy, and need to be placed on the ground, or on specially-constructed strong structures
5. Nutrient Film Technique (NFT)
• In this system, water from a fish tank is filtered and passed through the bottom of a horizontal
PVC pipe, in a small film. These pipes have holes cut on the top, in which plants are grown in such
a way that their roots dangle in the water flowing at the bottom. Nitrogenous wastes from the
tank water is absorbed by the plants, and since their roots are only partly submerged, this allows
them to be in contact with atmospheric oxygen as well. Purified water is then pumped back to the
fish tank. However, since there is no 'medium' for the roots to adhere to, this system requires
prior filtration to prevent clogs. NFT is only suitable for growing leafy vegetables and herbs which
have smaller root systems. Larger fruiting plants like tomatoes require a stable medium to adhere
to, and require more nutrients than is provided by tank water.
Pros
- Allows the continuous purification of water.
- Partially submerged roots have access to sufficient oxygen.
Cons
- Narrow channels or pipes are susceptible to clogging.
- In the event of pump failure or clogs, the roots may be deprived of water, causing loss of crop.
- Not suitable for larger, fruiting plants.
6. Raft/Deep Water Culture
• Raft systems, also known as Deep Water Culture (DWC) systems, use a 'raft' of polystyrene, which is floating in at least 1-foot deep water, to grow plants. The raft has well-placed
holes in which plants are grown in net pots, such that their roots are immersed in the water. This system can either have a raft floating directly in the fish tank, or have water
pumped from the tank to a filtration system, and then to channels containing a series of rafts. An aerator provides oxygen to both, water in the tank, and that containing the raft.
Since the roots have no medium to adhere to, this system can only be used to grow leafy greens or herbs, and not larger plants. It is the most popular system for commercial
purpose, due to the speed and ease of harvest. Large sections of greenhouses are devoted to tanks containing such rafts, and with time, they get pushed to one side, from where
mature produce is harvested. Seedlings are sown in holes from the opposite side of the raft. Thus, it operates like a conveyor system.
• Pros
- It offers high productivity at low labor requirement.
- Roots are exposed to the most nutrients in this method.
- It is the simplest and most economical of all aquaponic systems.
- Allows for efficient use of space, since raft can be placed in the tank itself.
- It is the most popular system for commercial production, but is also suited for home gardens and hobby applications.
- Plants are easier to harvest, since the roots are submerged in water, and not in any medium.
- Allows for higher stocking of fish, as purification occurs continuously.
• Cons
- Restricted to growing small, leafy greens and herbs like basil.
- Water is lost by evaporation at the gaps between raft edges and the tank it is kept in.
- Filtration is necessary, since the roots are completely immersed.
- Filtration process increases costs, besides requiring regular filter-cleanups.
- If the roots get covered with tank waste, it may be injurious to the plant.
- Roots are susceptible to microbial attacks, or may be consumed by herbivorous fish.
While these aquaponic systems work fine by themselves, they can also be used in combination to maximize the benefits of each type. An example of such a hybrid system is a fish
tank connected to a media bed, and then to an NFT pipe. Besides allowing cultivation of tomatoes or cucumbers, the media bed also filters water passing into the NFT pipe, in
which lettuce or basil can be grown. This prevents the need for installing and cleaning the filtration equipment for the NFT pipe.
