Aquaponics Q & A

What is aquaponics? Is it a better way to grow vegetables? What is involved in setting up an aquaponics system? What sort of maintenance is involved with an aquaponics system? Is it a costly way to grow vegetables? What sort of systems are out there on the market? What are some of the best systems and why?

1. What is aquaponics?

A name given to a plant growing system that uses the waste products from fish and crustaceans to provide the main nutrients required by the plants for growth, flowering and fruiting.
 

2. Is it a better way to grow vegetables?

Not always but if there is waste water from growing fish and crustaceans available then by using this resource there is a reduction in environmental waste
 

3. What is involved in setting up an aquaponics system?

A system that holds the fish and crustaceans, a method of utilizing the waste products from the fish and crustaceans and balancing the different requirements of the animals and plants in the two systems.
 

4. What sort of maintenance is involved with an aquaponics system?

Daily

• Feed the fish and crustaceans and observe their behaviour.
• Check water temperature and pH and record results
• Adjust pH if required
• Remove any dead fish and crustaceans
• Remove any solid wastes in the fish/crustacean system
• Top up with de-chlorinated water
• Check plants for health and remove any insects on plants
• Remove any dead leaves
• Harvest ripe fruit/vegetables
• Plant new seedlings as space becomes available
• Remove spent plants

Weekly

• Check E.C. And carry out water change to keep E.C. Within limits for fish/crustaceans and plants.
• Prune plants for optimum performance.
• Weigh or estimate weights of fish and crustaceans to determine optimum feeding rate for week ahead.
• Clean filters
• Check pumps and clean impellers/filters
• Check shade cloth covering

Monthly

• Check planting plan for month ahead and start seeding cycle.
• Harvest and or grade fish

Yearly

• Remove fish and crustaceans to temporary home
• Drain whole system and sterilize tanks/pipes/pumps using White King
• Empty grow beds and clean clay balls/gravel and containers and then sterilize with White King.
• Wash gravel/clay balls with plain water and allow to dry in sun before putting back into system.
• Refill system with clean water and run for 24 hours
• Check that all Chlorine has been removed.
• Re introduce fish/crustaceans into system
• Re-plant
• monitor pH, EC, Temperature and ammonia levels whilst introducing fish food into system and be prepared for water changes if ammonia spikes (depending upon fish species 0.1 to 1 Mg/L maximum)
   

5. Is it a costly way to grow vegetables?

Depends upon the scale of the operation and the length of the depreciation period.

It is better to start on a small scale and spend the minimum amount of money. Work out the capital cost and then the running costs and how much production you will have.

Example

Capital items

200.00   Tank for reservoir fish 1000 liters second hand
 50.00   Pump 240 volt 50 watts
 25.00   Timer
108.00   Air pump
 48.00   Airline and air stones and fittings
 30.00   Tubing/fittings
 30.00   Siphon
 15.00   Nets
150.00   Containers for medium 2 m x 2 m x 0.25 m 
 50.00   Stand for trays
 40.00   Medium – gravel 50 %
350.00   Medium clay balls 50 %
 25.00   Shade cloth/top/cover for fish

Running costs

  25.00   Seeds 
    9.90   pH test kit 
  26.00   pH down 1 liter
150.00   Fish fingerlings 50 @ 3.00
100.00   Fish food to produce 5 kg fish weight 
  31.94   Electricity 50 watts 1 hr day one year @ 25c
535.55   Electricity 35 watts 24/7 one year @ 25c
    9.00   Annual clean White King 1 L

Annual production

                100 loose leaf lettuce per average 4 weeks
1,430.00   100 X 52/4 = 1300 @ $ 1.10 wholesale

                100 bunch herbs per average 8 weeks
  585.00    100 x 52/8 = 650 @ $ 0.90 wholesale 

The setting up costs would normally be written off over 4 years (25% depreciation per annum) so for the first year the maths would be

2,015.00    Income
   280.25   Annual depreciation  1,121 @ 25%
   887.39   Annual running cost 
   847.36   “Profit”                                                                       

BUT the “profit” has to repay all the labour that was used to set up and run the operation so let's look at these items

Set-up the system, find the bits and pieces say 18 hours @ 12.00 = 216.00

Daily/weekly/monthly tasks say average 20 min/day 109.5 @ 5.76= 631.36

So if you can get the income then it is a good hobby :-)
 

6. What sort of systems are out there on the market?

A very wide variety from little hobby systems that attach to a fish tank costing under $ 100 to large NFT lettuce growing systems that can cost over $ 10,000
 

7. What are some of the best systems and why?

One needs to distinguish between hobby systems and semi-commercial systems. To the best of my knowledge there are no commercial aquaponic systems that have a proven track record of being commercially viable in Australia.

The best systems are simple systems that minimize the use of external power and have been built using second hand and recycled materials.

Keeping fish and crustaceans alive and healthy and growing over a long period of time is not easy unless their environmental conditions are closely monitored and controlled. People tend to under- estimate the difficulty of successful aquatic cultivation. By comparison the growing of plants is much easier.

Robin Moseby