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The GrEAU Project: A Student Run Hydroponics Business

GrEAU, which is French for water, is hydroponic based agricultural business founded and run by the students of Mecatina School, a small school located in La Tabatiere, a village on the Lower North Shore of Quebec.

At Mecatina School in Tabatiere, students have built a hydroponic garden using cost and energy efficient methods, in order to supply the isolated community with fresh produce.

It’s hard to believe that only five months ago, GrEAU, the student-run business and hydroponic garden at Mecatina School, was just an idea.

“We started brain storming in early November,” said Christopher Wong, the Science and Technology teacher who supervised the project. It began when three of his students wanted to enter the Quebec Entrepreneurial Contest 2014. Their goal was to create a business that applied the technology and science concepts they had learned in class with their desire to improve their community.

Mecatina School is situated on the rocky coastline of La Tabatiere, on the Lower North Shore of the St. Lawrence River, where there is no access to the community by road. Goods and supplies are sent in by boat or airplane. When produce arrives, it tends to be old or harvested before it’s ripe, forcing residents to pay a high price for food with reduced nutritional value.

Wong’s students decided to establish an environmentally friendly hydroponic garden using GMO-free, certified organic seeds. By selling their crops at $2-$3.50, they would be able to support the business while offering the isolated community fresh vegetables and herbs at a lower cost than what they would normally find in stores. The sustainable and efficient business also helps decrease the environmental impact from the transportation of food into the village.

Every Friday on their free period, one of the students delivers over 30 heads of lettuce, 10 bags of chives, 10 bags of dill and 10 bags of basil to the two local stores in the community. The veggies and herbs are organic, fresh and delicious, and it’s usually only a matter of days before the product is sold out.

The success of GrEAU came after months of hard work. Neither the students nor Wong has worked on a project like this before, so it was a learning experience for everyone. A great deal of research, planning and labour went into the garden’s construction. The students worked for many hours after school and even on weekends.

The team received a $300 grant from the CLC Initiative and a $1800 loan from the Governing Board (which has since been turned into a donation) in order to purchase their supplies. Starting in November and finishing by mid-March, the team constructed a system where up to 600 plants can grow at once in a 48 square feet space.

Despite its success, construction of the garden wasn’t always smooth sailing.  Wong said that one day, when him and the students went to purchase wood in -30 degree Celsius stormy weather, they ran into some difficulty. “We were carrying the sheets of plywood and the really bad winds made them act just like sails,” he said with a laugh.

So, what about the contest? To the student’s and Wong’s disappointment, they didn’t win. “When I found out, it was around April Fool’s day so the kids thought I was joking. I had to show them the email before they believed me.”

While the contest loss was a shock, the students are still working hard at GrEAU. The group, which has gained a fourth member since starting, will be examining the acidity of the water in the near future. They also recently purchased shirts with the GrEAU logo. “One of the students works at the store where we sell the produce and he spends about an hour talking to people in the community about GrEAU every shift,” said Wong.


With the numerous ways GrEAU gives back to the school, community and the students themselves, it’s safe to say that everyone involved is a winner.

See GrEAU’s website here, for more photos, their proposals and additional details about the business.

The Hydroponic Growing System
Hydroponics involves growing wants in nutrient water rather than soil. Although there are many benefits in growing plants in this manner, their are also some challenges that must be met.

Oxygen in the water is one of the most important necessities in any hydroponic system. If you were water your house plant too much it would probably die. This is because your plant would develop root rot. That is the growth of Anaerobic bacteria or bacteria that grows in the absence of oxygen. If oxygen is present, these bacteria will not grow or die (meaning they are obligate anaerobes).

DWC solves this problem by using air pump and air stones to bubble air through the water. The bubbles increase the surface area in which the oxygen can dissolve into the water. Kratky's method takes a different approach to this problem. Because all the pumps and stones will get expensive for large systems, Kratky's method does not require pumps of any kind. Instead it has a much lower water level with the plants hanging above. This leaves the majority of the roots exposed to air.

For our system we have a slightly higher water levels that reduce the need to monitor the water level as well as increase the amount of nutrients the plants take up. By incorporating Kratky's methodology we have been able to greatly reduce the amount of air pumps needed with a conventional DWC system.

The type of lighting is one of the most important factors that will affect the photosynthetic efficiency of our plants. As you can see in the graph to the right, only a certain portion of the visible light spectrum can be used to support photosynthesis.

Colour is often measured in Kelvin or K. Higher Kelvin lighting like 6000K produces more blue and purple light whereas 1500K lights produce more red light. Both produce photosynthetically active light but in our project we will be using 6000k lights as we are going purely for vegetative growth. The more red lights signal are similar to the type of sunlight you see around the end of the growing season. This tells the plants that winter will be coming soon and would make our lettuce bolt (start producing flowers and seeds) earlier.

Fertilizer c\Concentration and pH
As our hydroponic system is a closed system, we minimize the loss of water and has made fertilizer run-off a thing of the past. We simply need to replace any water and nutrients the plants use as they grow.

To do so we measure the ppm (parts per million) of dissolved solutes and calculate precisely how much nutrients we need to add. By doing so we can keep the nutrient levels at optimal levels consistently (1250 ppm +/- 100).

pH is also very important as plants prefer slightly acidic water at a pH of 5.5 to 6.0. To determine exactly how much acid is needed in the water we tried to calculate it using the formula pH= -log[H+] but because of the presence of buffers we needed to perform an acid-base titration, graph our data and use the graph to extrapolate the acid requirements needed for a given pH.

Temperature Control
High temperatures can drastically reduce the productivity and taste of most vegetation. This is because of the enzyme rubisco (or ribulose biphosphate carboxylase oxygenase). This enzyme that normally fixes carbon dioxide into glucose (sugar) but as temperatures rise above 25 degrees Celsius this enzyme does its job in reverse. This makes lettuce get bitter in the later months of summer.

Because our hydroponic system is indoors we will easily be able to grow the best tasting lettuce all year round. Keeping the water cool also increases the amount of oxygen that can dissolve into the water as the solubility of gases decreases as temperatures increase.

GrEAU is a hydroponic based agricultural business founded and run by the students (4) of Mecatina School, a small school (43 students) located in La Tabatiere (a village on the Lower North Shore of Quebec). Please take a moment to visit their website and learn about more about their amazing project, from the business plan to a full photo gallery highlighting the entire project.

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