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Unit 2.3 Grow Bed Design

2. Aquaponic Systems
Grow bed designs

3. Three Grow Bed Designs Flood and Drain Float
Nutrient Film Technique (NFT)

4. Flood and drain

5. How flood and drain works
1) fish produce waste
2) water with nutrients and metabolic by-products is sucked into pump
3) the pump pumps the water up the up pipe
4) water moves through up pipe
5) water floods the grow bed
6) water continues to flood grow bed until water level reaches top of stand pipe; a siphon is created
7) water that has been cleaned by media and plants drains back into the fish tank

6. The Bell Siphon

7. How the Bell Siphon Works

8. How the bell siphon works continued

9. Flood and Drain Media filled bed Grow a variety of plants
All of the water and sludge from fish tank is pumped to bed
Ideal mediums
Chemically inert, porous, clean, and able to drain freely
Media used gravel, perlite, sand, cinder, LECA
The media filled bed becomes a biofilter
Over time solids break down into elements the plants need
Flooding brings fresh water and nutrients into the bed
Draining draws fresh oxygen into bed
Media is prone to eventual clogging
Leads to anaerobic zones that slows growth and kills plant roots
Periodically grow bed needs to be emptied and cleaned
No extra filtration limits amount of fish that can be raised

10. Flood and Drain System components Fish tank Media Grow bed Pump
Possibly a sump
Some systems use aeration

11. FLOAT

12. How Float works Recirculating water 24/7
Pump moves water from sump tank to fish tank
Flow in fish tank is regulated by ball valve
Water flows through fish tanks and rest of system back to sump via gravity
Fresh water added to replace water lost to evaporation and transpiration
Float valve in sump regulates the need for incoming fresh water
Without preventative measure small tilapia can get into raft tank and eat plant roots

13. Float Components In the UVI System
Multiple fish tanks
Conical bottom clarifiers used to remove the solid waste and uneaten food
No biofilter to collect solid waste
Mineralization tanks
Degassing tank
pH adjustment tank
Water pump(s)
Air blower(s)
Raft tanks

14. Nutrient film technique (nft)

15. NFT
Plants are grown in channels that a nutrient rich solution is pumped through
Plant roots kept moist by thin film of nutrient solution that passes by
With no growing media crucial that roots are kept moist
Ideal for lettuce, herbs, and other leafy crops
No growing media or soil give a clean crop with no washing necessary
Channels are waist high
Seeding, transplanting, harvesting are made easier

16. HOW nft works
Water from fish tanks flows through a clarifier or other mechanism to remove solid waste
Critical that a biofilter is used since there is no large surface area for the beneficial bacteria to colonize
Water is pumped from degassing tank to individual NFT channels
Water flows through channels and collects in drain pipe
Drain pipe flows into a sump tank where it is pumped back into the aerated fish tanks to collect more nutrients
Waste water is removed from the bottom center of the fish tank where solids tend to collect and flows into the drum filter
When water leaves the drum filter it enters the mineralization tank
The water slows as it passes through the tanks and netting allowing the fine solids to collect
From the mineralization tank the water enters the aerated degassing tank to remove gasses and then goes back into the NFT channels

17. NFT Components Fish tanks Micro screen drum filter
Mineralization tanks
Degassing tanks
2 pumps (if you are not using gravity to have water flow back to fish tanks)
Fish tanks will have to be lower than the channels meaning you will have to partially bury them along with some of the plumbing

18. Other information related to NFT
Due to low volume of water used you either raise 4 times more plants or ¼ of fish as a ratio for nutrient amounts (in comparison to the float system)
Plumbing may become an issue
Fine sediments may clog the channels which may require more maintenance time and water quality parameters will have to be monitored more closely due to higher concentration of nutrients in lower volume of water

19. Advantages and disadvantages of three systems
TYPE
GENERAL COMMENTS
ADVANTAGES
DISADVANTAGES
FLOAT
The float system is the most basic of the three systems
Inexpensive; easy to assemble; good for school projects
No room for aquarium light; can only accommodate small plants
FLOOD AND DRAIN
The flood and drain system, with the grow bed on top of the fish tank, can be visually stunning and makes an ideal, compact aquaponic unit
Looks nice, can accommodate aquarium light, works well for school project; compact; good choice for ornamental system
The number of plants you can grow is limited by the size of the grow bed; will be the most costly to build if built for aesthetics
NUTRIENT FILM TECHNIQUE (NFT)
If you want to use your desktop aquaponics garden to grow lettuce and herbs, the NFT system is a good choice
Grow trays, troughs, or gullies can be placed next to the aquarium or wall mounted; grow area can be expanded by adding more trays
Takes up the most space; if water pump quits the plant roots will quickly dry out and plant could die

20. Reference
Nelson, R. L. Aquaponic Food Production Raising Fish and Plants for Food and Profit Nelson and Pade, Inc. Montello, WI. Pgs
With contributions from John S. Pade