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This Instructable outlines the construction of an indoor hydroponic system, which is a design project by a team of four First Year Engineering Science students from University of Toronto. The system is conceptual and experimental, and has not been tested in actual use. It uses the NFT technique to grow plants in PVC gutters. The system is designed to grow plants by a window that does not have table already. If a table is present, the frame can be easily modified to sit on the table. Any suggestions from people more experienced with hydroponics would be appreciated!

Step 1: Parts and Materials List

Most of these parts can be bought at a Home Depot or equivalent. The pump, the tubes, and the "tee"'s might require access to a hydroponics supply store. Items such as the nutrient solution, growing baskets and medium depend on what you want to grow.
- A submersible pump with at least 5' head ( we used an EcoPlus Submersible Pump - 132 gph)
- 10' flexible vinyl tubing, 5/8'' outer diameter, 1/2" inner diameter.
- Three 1/2" plastic "tee" connectors.
- Two 10' traditional style PVC gutter. We designed the frame to be used with Canadian guttering, which have different dimensions than the USA equivalent.
- Nine 8' pieces of 2x4 lumber
- 3" wood nails
- Carpenters glue
- Corrugated plastics (Optional: if you prefer to have the gutter covered)
- Water reservoir (Optional: any suitable container will do)

The total cost of this design ranges from $90 to $130, depending on the amount of resources the users have that can be used in building this system.

Step 2: Mark and Cut the Wood

Layouts for cutting up the lumber are below (for 8' 2x4). The cutting can be done using a handsaw, but we used a table saw for our prototype. The frame was designed to be tolerant of imprecise cuts, so do not fret over an extra 1/2" or so.

Standard size of lumber has a length of 8'.  In order to minimize waste, it is recommended to plan the combinations before cutting.
- (x 2) 43.5" | 43.5" | 8" 
- (x 1) 40" | 40" | 7.5" | 7.5" 
- (x 4) 26.5" | 33" | 36"
- (x 1) 36.5" | 36.5" | 7.5" | 7.5" | 7.5"
- (x 1) 7.5" | 7.5" | 7.5" | 33"

Step 3: Beginning the Side Frame

To construct the frame, we began with the sides.

wooden pieces needed for the right frame:
- (x 1) 43.5"
- (x 1) 33"
- (x 2) 26.5"
wooden pieces needed for the left frame:
- (x 1) 43.5"
- (x 1) 33"
- (x 2) 26.5"

1. Line up a 33" piece with a 43.5" piece, on a flat surface.
2. lay the 26.5" pieces across at the locations shown in the specifications (for the right side)
3. checking all dimensions, glue and nail the joints. For now, only use a single nail, to allow for slight adjustment.
4. repeat for the left side.

When constructing the right frame, make sure the 43.5" piece is on your right, and 33" piece is on your left.
When constructing the left frame, make sure the 43.5" piece is on your left, and 33" piece is on your right.

Step 4: Finishing the Side Frames

wooden pieces needed for the left frame:
- (x 1) 36.5"
- (x 1) 40"
- (x 1) 43.5"
wooden pieces needed for the right frame:
- (x 1) 36.5"
- (x 1) 40"
- (x 1) 43.5"

1. Get the left frame. take the 36.5" piece and place it under the 6.5" piece and next to the shorter side (33" piece), lining up and marking the correct dimensions.
2. Lift up the frame, and apply glue.
3. Use the 7.5" pieces to help align the vertical pieces as shown in the picture.
4. Hammer the nails in.
5. Repeat the same procedure (Steps 1-4) for the 40" and 43.5" pieces in sequence.
6. Repeat the procedure above for the right frame.

Step 5: Adding the Gutter Supports

wooden pieces needed for the left frame:
- (x 4) 7.5"
wooden pieces needed for the right frame:
- (x 4) 7.5"

1. Get the right side frame, measure 6" from the top of the longest vertical piece (43.5" piece) and mark a line.
2. Similarly, measure 6" from the top of the remaining vertical pieces and mark them respectively.
3. Starting from the longest vertical piece, put glue under the line marked and place the 7.5" piece horizontally under the line. Hammer the nails in.
4. Repeat step 3 for the rest of vertical pieces on the same side.
5. In order for water to flow with the force of gravity, the PVC gutter is slanted at a ratio of 1:40, as recommended for a NFT technique.  Therefore, for the left frame, measure 5" from the top for all the vertical pieces, and mark the line for each.
6. Repeat steps 3 and 4 for the left frame.

Step 6: Joining Both Side Frames Together

wooden pieces needed for this step
- (x2) 33"

1. Make the two sides stand vertically as shown in the picture, with the shortest side (33") facing downward on the floor.
2. Measure a distance of 33" between the side frames (measured from outer side of each frame). Make multiple measurements to ensure that both frames are parallel.
3. Put glue on the 43.5" piece and place the 33" pieces at the location indicated in the picture. Hammer in the one nail for each side.
4. Put the frame in upright position on a flat ground to ensure that the structure is stable.  Once confirmed, hammer another nail in for each side.

Step 7: Setting Up the Crossbeams

wooden pieces needed for this step
- (x4) 36"

1. Put the system into upright position.
2. Put glue on the crossbeam supports.
3. Place the 36" piece on top of the supports and hammer the nails in.

Step 8: Reinforcing the Side Frame + Adding Drainage Gutter Holder

wooden piece needed for this step:
- (x 1) 33"
- (x 2) 8"

1. Place the 33" wood across the lowest existing support on each side of the frame, as shown in picture, by applying glue and hammering the nail in.
2. Apply glue to the edge of 8" woods, and place them on the side of the right frame (below the gutter support of the 36.5" and 43.5" woods respectively, refer pictures for more information). It would be a great to hold the 8" wooden piece to the right frame using a clamp while waiting for the glue to dry.

Step 9: Installing the Gutters

Piece needed for this step:
(x 5) PVC gutter with 40" each

Installing gutters for growing plants
1. Measure the PVC gutter to appropriate length (40", can be slightly longer) and mark it.
2. Using a small handsaw, cut the PVC gutter into the desired length. (Note: you might need someone's help to hold the flexible gutter to prevent slippage)
3. Repeat step 2 until you get 5 PVC gutters of 40" each.
4. Place the PVC gutter onto the frame, mark the location of wooden post relative to the gutter.
5. Remove the PVC gutter from frame, drill holes in gutter at the markings.
6. Perform the same action for all 4 gutters.  
7. Place them back to the structure, use a string to tie the gutters to the wooden post. (Alternatively, you can use nails to secure the gutters in place)

Installing gutters for drainage to reservoir
1. Place the gutter on the drainage gutter support on the side of the right frame, mark two reference locations (arbitrary).
2. On the structure, hammer nail in at the marking, but don't hammer the nail completely into the structure, leave some space to hook the gutter.
3. On the gutter itself, drill holes according to the marking.
4. Fit the gutter on the nail. The gutter will rest on the drainage gutter support.

Step 10: Installing Water Circulation System

Piece needed for this step:
- 20ft 1/2" ID vinyl tubing
- (x 4) tee connectors for 1/2" ID tubing
- paper clips (optional)
- water container
- 132 GPH water pump

1. Place the water container under the drainage gutter. Ensure that the side of water container that is parallel to the drainage gutter has enough length so that the water will not wet the floor.
2. Fill the water container with water, and place the water pump into the container.
3. Set up the water circulation system by attaching the tube to the water pump, and all the way to the top left frame of the design.
4. Measure the diagonal length between the rows, then cut the tube and connect them using the tee connector.
5. [Caution: make sure hands are dry] Turn on the power supply while holding the tubes to ensure water outlets are facing the rows of gutter.  This is to test if the water pressure is sufficient. If water cannot be pumped up, get a stronger pump, or watch out for kinks that impede water flow.
6. Using binder clips, restrict water flows to certain outlets that monopolise water circulation.  Through several experiments, you will be able to figure out the best configuration.  Refer to the image attached to see what we came out with.
7. Using string, tie the tubes to the side post of the frame.  Turn on the water pump again to check if everything is working.

Step 11: Get It Running!

We haven't had a chance to really evaluate the system's ability to grow plants yet. Some issues have to be ironed out, including making sure that the plants can access the water at the bottom of the gutter, if they are grown in baskets (some sort of sponge or capillary mat could do the trick). Other solutions include using a more powerful pump (we got the cheapest available) or placing end caps on the gutter to raise the water level.
<p>awesome work keep it up...keep growing and experimenting!</p>
<p>what size were your grow baskets?</p><p>Great project, I constructed something similar. </p>
How do you keep algae from growing with open top gutters?
Yes, The side to side drain is the most efficent. Also, how about . . . less angle too from left to right and top tray to bottom tray, then as soon as it runs off (into a container at the same level as the bottom tray) the &quot;solar powered&quot; 12v pump can run the water back up. Less angle=easier to pump the water back up. With a rechargeable battery backup (maybe?) it could be continuous.
I seen one similar to this only it was capped at each end and a tube ran from the top right to the one below it, then from that one on the left to the one below it. So it more or less made a serpentine effect. I allowed for more water and nutrients to stay in the trough for a longer period of time. I think the water was controlled by a timer as well.

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