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In this experiment, a recycled glass container and a plastic water bottle are transformed into a basic Kratky hydroponic system (a Deep Water Culture without an air pump). As the simplest of all experiments provided on this website, it requires the fewest supplies and tools.

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Step 1:

Gather the following materials and tools:

Materials

1) Glass jar (Here we used a Bick's pickle jar)

2) Plastic water bottle (ensure it is at least slightly wider than the glass jar's opening)

Tools

1) Sharp utility knife

2) Cutting board

3) Permanent Marker

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Step 2:

  1. Place the bottle, neck side down, into the jar.

  2. Trace outline of jar opening onto plastic bottle. 

  3. Ensure that the bottle, once cut, will not freely fall into the jar.

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Step 3 :

  1. Place the bottle on it's side and securely hold (with help if needed)

  2. Use the utility knife to carefully cut the top of the plastic bottle off 

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Note: Try to ensure that this cut is even as it will be tucked under the pickle jar lid

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Step 4:

  1. Using the permanent marker, draw a circle roughly 13mm (1/2") in diameter on the outside of the bottle lid.

  2. Use the utility knife to cut out the marked circle.

  3. Place the lid back onto the bottle neck.

 

Note: This will hole will allow the water to wick up through the paper towel to the seeds/plant)

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Step 5:

1. Use the permanent marker and trace a circle on the outside of the jar lid, leaving a 6mm (1/4 inch) lip

2. While using a cutting board, now cut out the circle using the utility knife. 

Note: the jar lid is used to secure the cut bottle in place. Leaving too small of a lip or cutting the bottle too high will not work as intended.

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Step 6:

  1. Cut a small piece of paper towel, roughly 13mm x 13mm (1/2"x1/2")

  2. Wet the paper towel and place a few seeds of your choosing in the center. Fold the paper towel and set aside.

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Note: A leafy green works best for growing in this experiment. A few examples are lettuce, kale, and spinach. However, other plants could work as well like most herbs.

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Step 7:

1. Cut a larger piece paper towel into a strip roughly 50mx100mm (2" x 4") 

2. Twist the paper towel into a wick. You can wet the paper towel first to help it retain its twist.

3. Carefully feed the tip of your twisted paper towel into the bottom of the plastic bottle lid. This wick will feed water to the paper towel containing your seeds, so it will need to make contact with both the seeds and the nutrient water.

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Step 8:

1. Place the plastic bottle top with the wick into the glass jar opening.

2. Secure the plastic bottle top in place by putting screwing on the jar lid. If your plastic bottle top is jagged or too tall you may have to trim it slightly to get an appropriate fit. 

3. Place your damp paper towel containing your seeds into the lid of the plastic bottle top. Make sure it is touching the wick.

4. Pour nutrient water over the seeds and fill the jar until the water is covering the bottom of the bottle cap.

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Note: Ensure you mix your nutrient water from according the manufacturers instructions. At the early stages, you should follow the concentrations for starting seedlings (usually a lower concentration)

Once the plant is established (meaning new leaves are appearing), the concentration should be increased.

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Step 9:

  1. Place the jar near a window or under a grow light.

  2. Ensure that the nutrient water is replaced weekly.

  3. If algae or mould form, carefully remove the plant, clean the all parts with soap and water, and replace the nutrient water and paper towel.

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Note: If you are growing in the winter where natural light is reduced, you will need to use a grow light to ensure the plant is getting the light it needs. On average plants need 6 to 8 hours of direct sunlight. For best results provide 12 to 16 hours of exposure to a full spectrum grow light.

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