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Emily small aquaponic system

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Top view of the Pink Hungarian Lettuce and strawberry plant growing in the expanded shale.

Abstract[edit]

This project was buidt as part of the engr 305 class in the Spring 2015 semester. In order to reduce my impact on the environment and grow some of my own food, I built my own small scale personal use aquaponics system. In order to reduce the cost of construction, I utilized everyday objects, most of which I already owned. The system only uses 12.045 kWh/year and generates enough food to supplement my need to go to the grocery store and buy salad greens. It requires very little maintenance. The only input into the system is the daily fish food feedings. In conclusion, the project was a success as it has demonstrated its ability to generate food and has fulfilled all of my criteria.

Background[edit]

The first time I, Emily Wood encountered an aquaponics system, it was on Youtube.com. It got me really interested in the idea of growing my own food indoors in a sustainable way. However, at the time I was a student living in the dorms at Humboldt State University and didn’t think I had the space, money or time to create my own system. Additionally, I would have to deal with somehow eventually dismantling it and moving the system when I left the dorms. The goal of this project was to build a functioning small scale aquaponics system that takes up minimal space inside my house. I currently reside in a small house in Arcata, California with three other roommates. The food grown is currently being used by my roommates and I. The project began on January 31st 2015 and was finished May 8th 2015.

Growing plants using fish, also know as, aquaponics, is a symbiotic process that utilizes the waste from fish and converts it into nutrients for the plants. Water is cycled from the fish tank up to a grow bed where bacterial colonies convert the ammonium from the fish waste into nitrates which get used by the plants in their growth process. This symbiotic relationship not only provides food for the plants, but also cleans and purifies the water enough for the fish to continue to safely reside in.

Problem Statement[edit]

The objective of this project is to demonstrate that you can build your own self sustaining aquaponics system relatively inexpensively, create a system that can be used in a small apartment or dorm room, can be easily transported to a new location and of course, generate edible food.

Project Evaluation Criteria[edit]

The following Criteria will be used to assess the success of this project. These criteria were chosen based on the personal needs of the owner. The scale (1-10) represents the importance level of meeting the constraint of each listed criteria.

Criteria Constraints Weight
(1-10)
Educational aspect Must demonstrate a working concept of how an aquaponics system functions
7
Maintainability Must be easy to maintain with little time and energy
7
Aesthetics Must be pleasing to the eye
9
Cost Must be between $0-$75
10
Vegetation Must be edible
10
Functionality Must successfully generate food
10
Transportability Must be easy to move to a new location
8
Size Must fit through a door frame
10

Literature Review[edit]

This is a review of the available literature pertinent to my small aquaponics system.

Aquaponics basics[edit]

Aquaponics is a known for being a sustainable method of producing edible vegetation and fish. It is similar to {hydroponics} in that both methods grow plants in cycled water instead of soil [1]. However, unlike hydroponics, the system is wholly dependent upon itself for the natural cycling of nutrients throughout the system. No additional outside input of nutrients is needed in order to balance and maintain the system since the system utilizes a biological nitrifying filter [2]. Additionally, there is no need to change out and waste the water if salt and nutrient levels get too toxic. The aquaponics system naturally filters and maintains itself. This is achieved via nitrifying bacteria that gradually build up and live in the grow media. There are two different types of bacteria, the Nitrosomonas and the Nitrobacter and they are essential in turning the ammonia laden fish waste into the nitrates the plants utilize. The Nitrosomonas are the ammonia-oxidizing bacteria and are the first step of the nitrifying process. They work to turn ammonia to nitrites. The second step, involves the Nitrobacter or “nitrite-oxidizing bacteria,” which work to break down nitrite into the nitrate that is used by the plants [3]. The bacteria break down the ammonia from the fish waste, and convert it into nitrates which the plants can then utilize. At the same time, the plants are working to filter out the nitrates from the water before it returns back to the tank[4]. This symbiotic process not only cleans the fish water, reducing the ammonia levels to levels that are safe for the fish, but also provides the necessary nutrients for the plants to grow. Aquaponics is an attractive option because once set up, the system can run efficiently on its own without additional human input (unless you are feeding your fish manually instead of a timed fish feeder). It has been shown to produce food just as efficiently as hydroponics system [5]. Additionally, in the long run, aquaponics systems can be a cheaper alternative to hydroponics because there is no additional costs associated with buying the necessary nutrients that must be added in order to maintain a hydroponics system. Aquaponics also has a water usage advantage over hydroponics because the water never needs to be dumped out and discarded. The only net addition of water in an aquaponics system is when the water level in the tank gets low due to evaporation.

Types of Grow Media[edit]

An appropriate type of grow media should be chosen for the size and needs of a system. The size of the filter substrate or grow bed for maximum ammonia removal is, for every 1 gallon per minute of recirculating water a square foot of filter surface is needed [6]. Many aquaponics systems use the same types of grow media as hydroponics. Popular choices of grow media include; gravel, river stone, crushed stone, expanded shale, expanded clay pebbles (hydrotons) and synthetic. The diameter of the grow media should be around 12-18mm. This size provides an adequate water retention to aeration ratio to prevent the roots from rotting or the growth of mould [7]. This size range is big enough to allow the root systems of plants to latch onto and grow. It also allows solid waste to pass through without getting clogged. Another aspect to keep in mind is to chose a grow media that is pH neutral so it won’t change the pH of your fish tank.

Types of Fish Used[edit]

The type of fish used in a system depends on several factors such as, how large your fish tank is, what climate you live in, what temperature water the fish survive in and whether or not you plan to harvest the fish as a food source. There are many different species of fish that can be used in an aquaponics system. Tilapia, blue gill, sunfish, crappie, koi, fancy goldfish, pacu, trout, carp, catfish and largemouth bass are just a few species that have proved to do well in an aquaponics set up [8]. Some fish like tilapia, do best in warm water so special considerations such as an addition of a heater must be kept in mind [9]

Types of Plants Grown[edit]

There are many different types of plants that can be grown in an aquaponics system. The limiting factors on what grows best are how many plants you plan to grow and whether or not you have enough fish to support the nutrient needs of the plants. Too little plants and you system won’t get filtered properly. Too many and your system cannot support healthy plant growth[10] One of the most common types of plants grown are leafy-green vegetables. Lettuce and spinach can easily be harvested because their leaves grow above the surface of the substrate. Other vegetables such as tomatoes, peppers, squash and snow peas grow well. Herbs are another popular choice and have been shown to do well. The only types of plants that do not thrive in an aquaponics system are root and tuber crops [11]

References[edit]

  1. Crontn, Greg. 2011. Aquaponics. Encyclopedia of Environmental Issues, Rev. Ed. 91-92.
  2. 1986. Nitrification. Oxford: Published for the Society for General Microbiology by IRL
  3. Harris, Larry, O. LeRoy Fyock1977. Nitrifying Bacterial Substrates for Hatchery Water Re-use. [Denver, Colo.]: Colorado Division of Wildlife, Fisheries Research Section
  4. Anonymous, . 2014. Recipe for Successful Aquaponics.Alternatives Journal. 40, no. 4: 53.
  5. Winkler, S. (2013). “How Aquaponics Works.” <http://home.howstuffworks.com/lawn-garden/professional-landscaping/alternative-methods/aquaponics2.htm> (Sept. 30, 2012)
  6. Harris, Larry, O. LeRoy Fyock1977. Nitrifying Bacterial Substrates for Hatchery Water Re-use. [Denver, Colo.]: Colorado Division of Wildlife, Fisheries Research Section.
  7. "What Is The Best Aquaponics Grow Media? - Ideal For Grow Beds." Home Aquaponics System. June 14, 2013. Accessed February 13, 2015. http://homeaquaponicssystem.com/basics/what-is-the-best-aquaponics-grow-media/.
  8. "Recommended Plants and Fish in Aquaponics." Nelson & Pade Aquaponic Technology, Systems and Supplies. Accessed February 13, 2015. http://aquaponics.com/page/recommended-plants-and-fish-in-aquaponics.
  9. Scott. "Top Ten Fish Used in Aquaponics Systems." Empowernetwork. September 1, 2013. Accessed May 6, 2015. http://www.empowernetwork.com/scottfan/blog/top-ten-fish-used-in-aquaponic-systems/.
  10. "Recommended Plants and Fish in Aquaponics." Nelson & Pade Aquaponic Technology, Systems and Supplies. Accessed February 13, 2015. http://aquaponics.com/page/recommended-plants-and-fish-in-aquaponics.
  11. 2013. Aquaponics. World Food : An Encyclopedia of History, Culture, and Social Influence from Hunter-Gatherers to the Age of Globalization. 49-50.

Construction[edit]

Construction of the project was relatively simple and only took two days to fully assemble and complete. Additional construction time was needed later on when a bell siphon was added.

How to Build[edit]

The following instructions explain step by step how to build the small aquaponics system.

How to Build the Small Aquaponics System
ImageStep
Barbednipple.JPG Step 1: Measure and cut PVC into three 20" sections, four 3" sections and 1 5" section using a hand saw.
Imageneeded.png Step 2: In one of the 3" sections, drill a hole for the threaded nipple and insert it.
How the PVC should look after assembly. Step 3: Assemble the 4 90o elbow and 2 tees to the cut PVC pieces.
These will be the drip points. Step 4: Measure down the center of the PVC and put a mark in 1" increments. Drill holes into the areas you marked.
Imageneeded.png Step 5: Near one of the four corners of the plastic tub, cut a 1" hole using. This is Where the drainage outflow will be located.
You want to create a water tight seal. Step 6: Insert a rubber washer onto the bushing. Insert the bushing into the 1" hole you created. Attach another rubber washer to the end. Screw the threaded connector onto the bushing to create a water tight seal.
Imageneeded.png Step 7: Attach an 90o elbow to the end of your 5" PVC piece and insert the piece into the threaded connector located at the bottom of the plastic tub.
Zip tie going through one of the holes and looping around the PVC drip piping on the inside of the tub. Step 8: Drill four holes (two on each side of the plastic tub near the top) where you will thread zip ties and anchor the drip piping. Put the zip ties in and secure the drip piping.
These are the materials needed for the bell siphon. Step 9: Build plastic bottle bell siphon
Side view of the plastic aquarium tubing attached to pump and nipple barb. Step 10: Attach plastic aquarium tubing to nipple barb and to the pump. Place pump into fish tank and plug pump into the 15 minute incremental timer.
This cycling process will allow the beneficial bacteria to build up. Step 11: Add your grow media substrate. Let fish tank cycle for about 4 weeks.
Finished aquaponics system with plants starting to grow. Step 12: Finally, plant your plants!





Timeline[edit]

In order to meet the goals and objectives of this project the following timeline was established.

1/31 Purchased PVC pipe, plastic tub, grow media
1/31 Initial construction and assemblage
2/1 Completed construction and assemblage
2/1 First test run of system before adding grow media
2/1 Washed grow media
2/7 Purchased 6 additional goldfish
2/14 Purchased plants
2/14 Separated soil from roots
2/14 Planted spinach, butterhead lettuce and Tuscan baby leaf kale
2/14 Began testing water pH levels
2/21 Began weekly measurements of plant height (compare to control group)
2/25 Calculated energy usage of the system (kWh used by water pump)
2/27 Obtained ammonia/nitrate/nitrite test kit
2/27 Started bi-weekly water testing for pH, dissolved oxygen, nitrate and nitrogen levels
4/3 Created and installed bell siphon
4/4 Bought Pink Hungarian lettuce and strawberry plant
4/4 Planted Pink Hungarian lettuce and strawberry plant
5/7 Harvested food

Costs[edit]

All of the items for this project have already been purchased. About half of the project materials were gathered from what I already had laying around my home. These items could be easily found at an aquarium store, craigslist, thrift store or garage sale rather inexpensively. The total cost did not take into account the local and state sales tax rate of where I bought the items (8.75%).

Quantity Material Source Cost ($) Total ($)
1 small make-up remover plastic bottle My house 0.00 0.00
1 plastic 16 oz. soda bottle My house 0.00 0.00
3 Schedule 40 PVC Pipe (4ft) Orchard Supply Store 0.32 0.96
5 90° elbow Orchard Supply Store 0.27 1.35
2 tees Orchard Supply Store 0.35 0.70
3 1"x1/2" slip joint rubber washers Orchard Supply Store 2.27 2.27
1 31 QT plastic tub Orchard Supply Store 11.99 11.99
1 3/4"x1/2" PVC bushing Home Depot 0.40 0.40
1 5/16" plastic aquarium tubing My house 0.00 0.00
1 threaded nipple- 1/4" barbs My house 0.00 0.00
1 1/4" galvanized steel screen (4"x6" used) My house 0.00 0.00
1 15 minute increment timer Hydroponic Warehouse 14.00 14.00
1 20lb bag 3/8" expanded shale Hydroponic Warehouse 21.00 21.00
6 zip ties My house 0.00 0.00
1 Pondmaster Pump (5.5W Hmax 30" Qmax 75GPH) My house 0.00 0.00
1 10 gal fish tank My house 0.00 0.00
1 aquarium heater My house 0.00 0.00
2 15"x 2"x 3/4" wood My house 0.00 0.00
6 goldfish Petco 0.07 0.42
18 plants Arcata Farmer's Market 12.00 12.00
Total Cost $65.09 USD

Operation[edit]

Maintenance[edit]

Maintenance of the grow bed, pump, plants, fish and water should be performed daily, weekly and monthly.

Schedule[edit]

Daily
  • Feeding of fish (once in the morning and once at night).
  • Checking temperature of water to make sure it is between 65-68 degrees Fahrenheit (for goldfish). Other fish may require different temperature water.
Weekly
  • Check the pH level of water. It should be Between 6.8 and 7.0.
  • Check plants for any bugs or insects.
  • Check ammonia levels. Levels should be at or below 0.5ppm.
Monthly
  • Check nitrate levels. Levels above 150ppm could indicate that your system does not have enough plants.
  • Check to make sure the pump is working properly.
  • Check to make sure piping and tubing are not leaking.
  • Check to make sure siphon is in place and working properly.
  • Harvest food
  • Add additional water to tank when level gets low
Yearly
  • Buy additional fish
  • Plant new plants

Instructions[edit]

How to Maintain Your Small Scale Aquaponics System
ImageStep
Test for ammonia Step 1 : Check Ammonia levels once a week to make sure they are not reaching toxic levels.
Removing aphids on plant Step 2 : Check plants for any bugs and remove them as needed.
Replace evaporated water Step 3 : Add water to fish tank when level starts to get low.
File:.jpg Step 4 : Check pH level periodically.
Lettuce growing bigger Step 5 : Harvest and enjoy your food when plants get big enough.

Conclusion[edit]

This section is a discussion of the results obtained from testing and analysis throughout the duration of the project. It also includes the next steps that must be taken, lessons learned and some basic troubleshooting methods if problems arise.

Testing results[edit]

Water Quality[edit]

PH
Date Fish tank
2/28/15 7.64
3/14/15 7.28
3/28/15 6.90
4/11/15 6.83
Nitrogen
Date Fish tank
2/28/15 15ppm
3/14/15 15ppm
3/28/15 15ppm
4/11/15 15ppm
Nitrate
Date Fish tank
2/28/15 65ppm
3/14/15 64.5ppm
3/28/15 67.5ppm
4/11/15 65ppm
Dissolved Oxygen
Date Fish tank
2/28/15 3.8ppm
3/14/15 3.3ppm
3/28/15 3.5ppm
4/11/15 3.9ppm

Bell Siphon Test[edit]






Plants[edit]

After the system cycled for four weeks, I planted the first plants. In order to expedite the grow process, I opted to plant starter plants I bought from the Arcata Farmers Market. This meant the plant roots had to be separated from the soil they were growing in.

I planted spinach, butterhead lettuce and Tuscan baby leaf kale. The first few weeks I noticed plant growth, but after week four, the butterhead lettuce began to wilt. Additionally, the kale's leaf growth seemed stunted. At this point I decided to build and install a bell siphon to get more aeration to the plants root system.

After installing the bell siphon, I replanted the remaining lettuce and added a strawberry plant to experiment some more with different types of plants.


Calculated Energy Use[edit]

I used a small standard pond pump for my system. It is rated at 5.5 watts. It is on a timer that turns on for 15 minutes every hour.

  • 15min/60min x 24hr = pump on for 6 hours everyday.
  • 5.5 watts x 6hrs/1000 = 0.033kWh
  • 0.033kWh x 365 days = 12.045 kWh per year.

Lessons learned[edit]

If done differently, next time I would have created the bell siphon earlier on. This would have presumably helped my spinach grow a lot better because their roots would have more time exposed to the air. It is essential that plants roots receive enough aeration. Another lesson learned was that the location I initially chose was not ideal. I would have moved the system to the sunnier kitchen area a lot sooner. Another way I could have planned for an ideal location would have been to purchase something like the Luster Leaf 1875 Rapitest Suncalc Sunlight Calculator to determine where in my house would get the optimum amount of sunlight.

Next steps[edit]

Next steps are to continue to harvest and enjoy my food. Additionally, I will continue to monitor the water quality throughout the lifetime of my system.

Troubleshooting[edit]

This is only how to troubleshoot basic operation.

Issue Solution
Pump stops working First, make sure it is plugged in. Then take it out of tank and smack it on the palm of hand while running it under clean tap water. This will help loosen and unclog any trapped debris.
Fish start to die Temperature may fluctuate, especially with a small volume tank. If water gets too cold or too warm, make sure to adjust temperature accordingly. You may want to purchase a small tank heater.
Too much ammonia may have built up. To fix this, add more plants and don't over feed your fish. Too many fish and your systems' biofilter will not work efficiently.
Plants get bugs Feed them to your fish or spray them off with water.
Toxic ammonia levels reached. Stop feeding fish for a day. Also, remove any dead fish if present. Change a portion of the water out to dilute the ammonia.

Team[edit]

This was an individual project completed at the users' home during the Spring 2015 semester.