Disclaimer: Please note and abide by copyright laws. Some items contained in these presentations are taken from copyrighted material without express permission of redistribution. These slides are archived here for your use in educational activities. Although an educational use exemption would apply, presentations are catalogued here for educational purposes only. Unit 2.3 Grow Bed Design

Aquaponic Systems Grow bed designs

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

Flood and drain

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

The Bell Siphon

How the Bell Siphon Works

How the bell siphon works continued

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

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

FLOAT

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

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

Nutrient film technique (nft)

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

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

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

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

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

Reference Nelson, R. L. Aquaponic Food Production Raising Fish and Plants for Food and Profit. 2008. Nelson and Pade, Inc. Montello, WI. Pgs. 45-64. With contributions from John S. Pade