Cost/Benefit Analysis ofAquaponic SystemsRichard Chiang1

PURPOSEThe purpose of this paper is to analyse the costs and benefits of aquaponic systemsdesigned for home use. However, one can easily extrapolate from this paper thecommercial benefits of aquaponic systems in comparison to other ways of farming fishand vegetables.Furthermore, with climate change (carbon emission), food shortages, water shortages,depleting fish stocks and increasing energy cost becoming critical problems andissues facing the world, one can see that aquaponic systems are one obvious solutionto reducing their impacts.The aquaponic systems used in this analysis are based on:1. Those available from Backyard Aquaponics of Western Australia;2. Current or most recent cost and price figures in Perth, Western Australia; and3. Climatic conditions in and around Perth.This paper does not intend to provide details on how to set up or use aquaponicsystems. Interested readers should refer to extensive literatures on this subjectavailable elsewhere.I like to thank Mr Joel Malcolm, Mrs Faye Arcaro and Mr Carl Schmidt of BackyardAquaponics, corner Jandakot Road and Berrigan Drive, Jandakot, Western Australia6164, for the assistance rendered to me in preparing this paper. Unless otherwisestated, all figures used in this paper are provided by them or extracted from theirdocuments.This paper is dedicated to Mr John Brummell OAM, Coordinator Fusion Horticulture,Canberra ACT. I hope this paper will be of some assistance to him in his worthwhileeffort to popularise aquaponics in Australia. In his letter to me, he stated “I am morethan convinced that aquaponics is one way to go . combat climate change watershortages . food shortages .”.INTRODUCTIONIn an aquaponic system, nutrient-rich waste water from fish tanks is used to provideplant food to vegetables and herbs grown hydroponically in grow beds. Beneficialbacteria in the grow beds convert ammonia to an available form of nutrients able to betaken up by the plants. The removal of nutrients (fish waste, algae and fish feedleftovers) from the water allows the freshly cleaned water to be recirculated back intothe fish tank. A series of pipes, irrigation fittings, stands and water pump enable this.2

The material inputs to the aquaponic system are essentially fingerlings (young fish),fish feed, seedlings and water (to replace loss in evaporation and transpiration and toproduce fish, vegetables and herbs) while nothing is wasted.Other cost input to the aquaponic system is power supply which is required to run thewater pump and air pump.After installation of the aquaponic system, the major effort involved is the initialestablishment of the grow beds and the fish tank with vegetables and fish fingerlingsrespectively in the first year. Once established, the aquaponic system virtually runs byitself and less than 30 minutes a day is required to keep the system going. Thismainly involves feeding the fish daily and occasionally harvesting the fresh vegetablesand fish when fully grown.I use the high ends of the cost figures and the low ends of revenue figures to arrive atthe financial benefits.Hence, the return on investment may be consideredconservative.BACKYARD AQUAPONIC SYSTEMSThe main features of the aquaponic systems used in this exercise and derived powerconsumption and cost figures are summarised in Table 1 below:Table 1Backyard Aquaponics lyTheDeluxeNo. of Grow Beds12346Fish Tank Capacity (kL)11233Fingerlings TankNoNoNoYes500 LitresWater Pump Capacity (kL/hr) Pump Wattage606065250250Estimated Water Pump PowerConsumption pa1 (KWH)132132142548548Air Pump Capacity (litres per minute)88888Air Pump Wattage1010101010Estimated Air Pump PowerConsumption pa (KWH)8888888888Total Estimated Power Consumptionpa (KWH)220220230636636Estimated Cost of Power pa2 39 39 41 112 1121Assume water pump runs for 15 minutes in every hour.2Base on the cost of power in Perth, Western Australia, at 17.61 cents per KWH on 1st August 2009.3

FISHFish species that are considered suitable for aquaponic systems in Western Australia,derived fish costs and market prices of live fish in Perth are summarised in Table 2below:Table 2Silver PerchBarramundiRainbowTroutBlack BreamGoldfishFreshSalt or freshFreshSalt or freshFreshAll year roundOct – MarApr – SepAll year roundAll year round10 – 126–86–824-500450 – 500450 – 500500-Temperature Range20C – 350C150C – 390C00C – 230C80C – 330COptimumTemperature Range200C – 300C270C180C220C – 240C160C – 220CType of PelletisedFeedsFloating orSinkingFloating orSinkingFloating orSinkingSinkingFloatingApproximate FeedConversion Ratio(Feed : Fish)2.00 : 1.001.70 : 1.001.25 : 1.00(Not available)-Other FeedsOmnivorous/plant materialsas adultsCarnivorousCarnivorousCarnivorousAlgaeCost of EachFingerling 2.00(8 cm/50gms) 4.50(300 gms) 1.30(10 cm/50gms) 4.00 - 5.00(300 gms) 1.30Fish SpeciesWaterGrowth Time of YearNormal GrowthPeriod (months)Normal HarvestingGrowth Size (gms) 1.00- 1.50(3-4 cm)Approximate Cost of1 kg of Fish Feed 3.00 5.00 4.00 Approximate Cost ofFeed to Produce 1Fish3 (500 gms) 2.70 1.70 2.25 Total Cost of Feed for1 Fish (500 gms)plus 1 Fingerling 4.70 6.20 3.55 Retail Price4 of 1 LiveFish (500 gms) inPerth (Low End) 12.00 9.00 It is clear from the above figures that Rainbow Trout and Barramundi are ideally suitedfor aquaponics in Perth from their excellent feed conversion ratios, short growth3Larger fingerlings of the respective fish available are used and the difference in weight between the fingerling and the fishis used to derive the fish feed required and hence the cost of fish feed.4These are the lower end of current retail prices of respective live fish in Perth from a phone survey.4

periods and complementary growing time in the year. Hence, I prepare this paperbased on these two species of fish only.COSTSCapital CostsThe initial one time capital cost for each of the Aquaponic System is summarised inTable 3 below:Table 3Backyard Aquaponics SystemPriceDelivery & InstallationTotal TheDeluxe 1,845 3,100 4,995 7,525 9,975 425 675 975 1,300 1,500 2,270 3,775 5,970 8,825 11,475Other CostsCost of FishIn costing the fish, it is assumed that the Barramundi will be kept in the warmer monthsof the year (November – May/June) and Rainbow Trout will be kept in the coldermonths (April – October).Table 4Backyard Aquaponics lyTheDeluxeNo. of Barramundi5 pa20 – 25Average:2240 – 50Average:4560 – 75Average:6780 – 100Average:90120 – 150Average:135No. of Rainbow Trout pa20 – 25Average:2240 – 50Average:4560 – 75Average:6780 – 100Average:90120 – 150Average:135Cost of Barramundi at 6.20 eachfrom Table 2 based on Average(High End)Cost of Rainbow Trout at 3.55each from Table 2 based onAverage (High End)Total Cost of Fish (Barramundi Rainbow Trout) pa (High End) 140 280 420 560 840 80 160 240 320 480 220 440 660 880 13205Assume fish are raised under favourable conditions, 40-50 fishes (Barramundi and Rainbow Trout, half each) pa per growbed and each fish weighs 450-500 gms at harvesting.5

Cost of Seedlings for Vegetables and HerbsTable 5Backyard Aquaponics SystemCost Estimates of Seedlings pa(High End)TheCourtyardTheEntertainerTheBackyard 60 120 180TheFamilyTheDeluxe 240 360Cost of WaterTable 6Backyard Aquaponics lyTheDeluxeEstimated Evaporation andTranspiration Water Loss pa6 (kL)0.550.551.101.651.65Estimated Water Consumed byfishes, Vegetables and Herbs pa7(kL) (High End)0.551.101.652.203.30Total Estimated WaterConsumption pa (kL) (High End)1.101.652.753.855.95Estimated Cost of Water8 (HighEnd) 0.70 1.10 1.80 2.50 3.60The statement from Geoff Wilson at Footnote 7 means that about one kilo of fish andseven kilos of vegetables and/or herbs can be grown for every 22 litres of waterwhich cost less than one cent in Perth. One can therefore see how small is thequantity and cost of water used in an aquaponic system!Summary of Other Costs6This is based on statements “Temperate climate evapo-transpiration water loss in aquaponics has been cut to around 0.15%a day. This means that top up of water each year is about 55% of the total water volume in the system” from Geoff Wilson,Convenor, Aquaponics Network Australia, 17th February 2006.7This is based on the statement “About one tonne of fish and seven tonnes of vegetables or herbs can be grown for every 22cubic metres (22,000 litres) of water” from Geoff Wilson, Convenor, Aquaponics Network Australia, 17th February 2006.Hence 50 fishes (Barramundi or Rainbow Trout) which weigh around 25 kgs use 550 litres of water.8This is based on cost of water at 0.643 per kL in Perth, Western Australia, on 1st August 2009.6

You will note that I have not included the cost on labour provided by the owner of theaquaponic system. As stated earlier, less than 30 minutes per day will be required tokeep the system going. This mainly involves feeding the fish.Table 7TheCourtyardTheEntertainerTheBackyardEstimated Cost of Power (Table 1) 39.00 39.00 41.00 112.00 112.00Estimated Cost Fish Fingerlings(Table 4) 220.00 440.00 660.00 880.00 1,320.00Estimated Cost of Seedlings (Table5) 60.00 120.00 180.00 240.00 360.00Estimated Cost of Water (Table 6) 0.70 1.10 1.80 2.50 3.60 320.00 600.00 883.00 1,234.00 1,796.00TheFamilyTheDeluxeBackyard Aquaponics SystemTotal Other CostsTheFamilyTheDeluxeRETURN ON INVESTMENTTable 8Backyard Aquaponics SystemTheCourtyardTheEntertainerTheBackyardRetail Value of Live Barramundi paat 12.00 each 264 540 804 1,080 1,620Retail Value of Live Rainbow Troutpa at 9.00 each 198 405 603 810 1,215Retail Value of Vegetables andHerbs pa 800 1,600 2,400 3,200 4,800Total Potential Retail Revenue 1,262 2,545 3,807 5,090 7,035 900 1,900 2,900 3,800 5,2002. Potential Net RevenuePay Back Period(years)2.5COST/BENEFIT ANALYSIS7

The financial analysis shows that the Pay Back Period is approximately the same forthe Backyard Aquaponic Systems and is just more than 2 years, especially for thosewho value fresh vegetables and live fish and are prepared to pay the market prices forthem.In addition, the aquaponic systems have the following benefits:1.Aquaponic systems use very little water. Hence, they could be used to:a. Produce fresh food using very little water; andb. Produce fresh food in places which are short of water.2.The owner can achieve truly sustainable farming in his own backyard.3.The owner can have ready and immediate access to fresh vegetables andlive fish at his backyard when required, i.e. he doesn’t have to drive to theshop to buy them.4.Once established, it requires very little effort and time to run the system –only effort required is to feed the fish daily.5.The aquaponic system can be set up on a small area around the houseand at the backyard, even on places that are deemed too small for homegardens.6.Just about every household in Australia can have an aquaponic systeminstalled in their house.7.The owner can be sure of the health quality and freshness of the fish andvegetables that are chemical and pesticide free.8.Comfortable working height suits disabled as well as elderly people.9.No chemical fertiliser is used for growing vegetables and/or herbs.10.No nutrient is wasted in aquaponics.11.Educational benefits include teaching children how to grow food as well ascare for living things.12.No ongoing soil improvements required, saving time energy and money13.Raised beds keep plants free from ground dwelling pests.14.It provides a topic for conversation and entertaining guests at thebackyard.15.The owner contributes to:conservation of the scarce water resources – only use 10% of waterrequired to grow vegetables on the ground;environmentally friendly way of growing food;cost-effective production of food locally;cost-effective use of energy;cost-effective use of idle places around the house; andclimate change management.a.b.c.d.e.f.The aquaponic system will be more cost-effective if fish feed can be cost-effectivelyproduced locally through the use of worm farms and the like.8

There is also no doubt that large scale production of fish and vegetables by aquaponicmeans will result in better return on investment. This can be done locally at a village,town, city or regional level to reduce transport time and cost.RISK MANAGEMENTPower CutsFish has a high requirement for clean water and dissolved oxygen. Their survival timeis determined by the size of the fish, the temperature of the water, time of day,ammonia and oxygen levels.Hence, it is necessary to have a back up system to the power supply. This may be inthe form of a generator, battery back up, solar or wind power. It is advisable for theowner to have such a backup power supply system in case of a prolonged power cut.All aquaponic systems supplied by Backyard Aquaponics comes with a battery backup to their air pump so that it can continue to run during power cuts of few hoursduration each.Water CutsThe fish tank of an aquaponic system has to be topped up once a week in Summer.The water sources may be from the bore, scheme or rain.Water storage may be required for an isolated location, collected in Winter and used inSummer. Water can also be trucked in if required.There are very few such problems in the Perth Metropolitan area.PestIt’s best to use “Integrated Pest Management” where predators and parasites areencouraged to visit an aquaponic system and help to keep a natural balance. Iftreatments are required, they must be fish friendly. As the beds are raised there is lesschance of ground dwelling pests.Hygiene is also important and good management practices minimise the spread ofpests and diseases. This includes picking off the caterpillars and feeding them to thefish.The washing off the soil from plant seedling roots before adding to the system alsoeliminates most soil borne diseases.Treatments that may be used include the followings: Fungicide and bloom stimulant- Eco-rose 20.00 Caterpillar treatment- Dipel 18.50 Traps for aphids and whitefly- 10.00 to 20.009

Beat-A-Bug Chili and garlic spray Seasol - Seaweed concentrate- 13.50- 8.20Fish Sicknesses and DiseasesMonitoring fish behaviour could be done while feeding fish daily and one can get toknow whether the fish are behaving normally or not. Signs of flashing, not eatingand/or gulping at the surface are indications that something may not be right.Management may include simple salt treatments. If only one fish is affected, it shouldbe removed from the system. Fish introduced in stages could be quarantined first.Salt treatments for a family system are less than 10.BreakdownsIt is advisable to have a spare pump on hand. Maintenance should include periodchecks to ensure back up system is working.EstablishmentOnce an aquaponic system has been set up and the fish tank filled with water, it isadvisable that seedlings are planted into the grow beds preceding the addition of fish.Rates for fish stocking densities are 20-25 fish per grow bed and it is best they areadvanced fingerlings (around 100mm). The system will go through a natural cyclecalled nitrification and can be monitored and documented to track whether the systemhas become cycled. This process can take as little as short 4 weeks dependant onconditions and temperatures. To avoid establishment problem, these advices shouldbe followed as far as possible.Other Risks1. Contamination from neighbouring sprays may be avoided by enclosing in agreenhouse to avoid and protect water quality.2. Vandalism risk can be minimised by construction of fences to keep unwantedvisitors away.3. Birds going for the fish. Protective netting may be set up over the fish tank aswell as placing a floating raft at the fish tank to allow fish a place to hide.CONCLUSIONIt is clear that aquaponics is very cost-effective for growing vegetables and raising fishat homes with numerous benefits. Moreover, aquaponics also allow families toindividually contribute to overcoming worsening water and food shortages and climatechange problems facing Australia and the world.Furthermore, larger aquaponic systems could be established for villages, towns,regions, etc, to more cost-effectively serve local food needs.10

Governments, businesses and individuals alike should therefore support andencourage the use of aquaponics at all levels.Richard Chiang9Bachelor of Surveying (Honours), University of QueenslandPostgraduate Diploma in Computer Science, University of QueenslandPostgraduate Diploma in Applied Finance & Investment, Securities Institute of AustraliaCertificate in Financials Advising Essentials, Securities Institute of Australia16th November 20099Richard is a retired public servant after working for more than 30 years for the Governments of Malaysia and WesternAustralia.11