Water and the Aquaponics System

Food for Thought: K-12 Aquaponics Program

Linda Chilton

USC Sea Grant Education Programs Manager

April 2017

Objectives of this lesson

�  Reflect on the role water plays in supporting life on our planet and more specifically in food supply

�  Learn the importance of preparing the water in your aquaponics system and how to monitor the health or quality of the water

�  Begin to explore the flow of water in the system

�  Begin to explore the relationship between water and food justice

Aztecs farmed “floating” islands

Chinampas today

�  rice fields + fish + birds that began as early as 6th century in Southern China

Similar farming practices today

What do you notice is similar between these three systems?

Hydroponics – Large scale plant production with nutrient solution and without soil

Aquaculture Large scale fish, crab, lobster, snail and clam farming

� Aquaculture + Hydroponics = Aquaponics � Aqua: from Latin for water �  ponics: from Greek, to work or labor; refers to

roots growing in water, without soil

Aquaponics

Aquaponics

�  raise both animals and plants �  nutrients produced are used

by the system �  everything cycles �  less water, less power needed

•  less expensive then hydroponics •  creates natural nitrogen balance

�  Plants

�  Microbes

�  Fish

�  Pump

Why Do They Need Water?

Water Circulation

�  Using the large sheet of paper create a model of water circulation in your tank. How does water move through the system? Remember to label all of the processes and interactions.

Talk With Your Partner

�  Discuss how you can decide which water to use to put into your system? ¡  Can you use water from the tap? ¡  From the hose? ¡  Do you need bottled water? ¡  Do you need special water? ¡  Can you use LA River water?

�  How can you be certain the water is healthy for your aquaponics system and the life in your system?

�  Clear water doesn’t always equal healthy water!

Talk With Your Partner

Water Test Kits

�  Used to measure water quality – the health of the water. The water test kits use reagents that are added to the sample of water to find the levels of important parameters of:

- dissolved oxygen - nitrite - nitrate - alkalinity - ammonia - temperature - pH

•  Oxygen is essential to support healthy fish, roots, and microbes. •  Dissolved oxygen is measured in parts per million (PPM) or milligrams/liter (mg/l). Oxygen levels change rapidly once a sample is taken from the system. •  Temperature, pressure and elevation all effect how much oxygen can stay dissolved in water.

• Pumps and splashing water increase oxygen availability. • Less oxygen stays dissolved in warmer water

Dissolved Oxygen

http://www.teamorca.org/

pH (potential Hydrogen)

�  amount of free hydrogen or free hydroxyl ions (how acidic or basic a solution is respectively).

�  pH impacts ¡  plants ability to absorb nutrients ¡  animal and microbe health

�  The pH scale is 0 – 14 with 7 as neutral; ¡  plants do better at a lower pH

�  The amount of salts (softness or hardness of the water) effects the stability the pH of the water.

Acidic

Basic

Neu

tral

Temperature

�  Water temperature ranges for fish and microbes must be monitored

�  Different species of fish, have different temperature needs based on their native habitat    

species Trout Tilapia Goldfish

Thriving temperature (surviving temperature)

55 – 65oF

(38-68°F)

74 – 80oF

(60-95°F)

65 – 75oF

(45-90°F)

�  Temperature effects: ¡  the ability of bacteria to convert ammonia to nitrates that can be used by plants

¡  Oxygen availability in water for fish, roots, microbes

�  Time of day, heat of the room can both effect temperature. �  Most fish can handle wide temperature changes over several

hours but not rapid changes.

Temperature

Measuring Nitrogen

�  Nitrogen can be found in three forms in your system so we measure all three ¡  Ammonia – from fish wastes and decomposition; high levels

can be deadly to fish ¡  Nitrite – after bacteria convert the ammonia to nitrite; still a

problem for fish ¡  Nitrate – a form of nitrogen plants can use to grow and not

harmful to fish in limited amounts

Changes in Water Quality

�  What might change in your system from morning to afternoon that would change water quality?

�  What other clues can you use to tell the water quality is

changing, before you do a test?

�  As we look how does this project effect the world in which we live, we are looking at an alternative to conventional farming.

�  70% of freshwater used goes to agriculture �  Roughly 30% of the food produced worldwide  (about 1.3 billion

tons) is lost or wasted every year, which means that the water used to produce it is also wasted

�  When we look at water on a world scale, water scarcity directly impacts food security

�  Global food and nutritional security, requires producing more nutritious food with less water

�  Aquaponics is one alternative to conventional farming that uses significantly less water.

Water & Food Production

�

Linda ChiltonEducation Programs Manager

USC Sea Grant

lchilton@usc.edu

Questions?

Thanks for a productive day!