What is a GrowTube?

A GrowTube is a compact and easy to build hydroponic system that allows you to grow a wide variety of plants in a soilless environment.
It is made from freely available materials and you can build it yourself with hand tools.

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How to build your own GrowTubes

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All the materials that you will need, are available from your local hardware or building supplies store.

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Follow the instructions below to build yourself two GrowTubes out of a single length of PVC pipe.

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Parts & Materials needed

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1. ​6meter length of 110mm PVC pipe.       1qty

2. 110mm female pipe end-caps                4 qty

3. float valves                                                2 qty

4. 1meter length of 75mm (3") PVC pipe   1 qty

5. PVC glue                                                   1 tube

6. Plastic storage crate with lid (20 liter)     1 qty

7. 15mm tank fitting                                     1 qty

8. 15mm hose pipe                                      5 meter

9. 15mm barbed fittings                              4 qty

10. 50mm net cups                                        48 qty

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Tools needed

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1. 75mm hole saw

2. 21mm hole saw

3. Cordless or power electric drill

4. Mitre saw or hand plane saw & mitre box

5. Marking pencil

6. Tape measure

7. 100 grit or similar sandpaper

8. Paper clips

9. 5meter length of thin string.

10. Jigsaw (optional)

11. De-burring tool (optional)

12. Smooth, flat piece of wood, 300 x 100 x 20mm approx.

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Part 1: Pipe construction

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Method

Pipe Preparation

1. 110mm sewerage pipes normally come in 6m lengths but such long lengths become unmanageable and difficult to move around, so I cut it in half to make two GrowTubes from a single length of pipe.

2. If the ends of the pipe are not already square, trim them by cutting small pieces (5mm) off either end of each pipe.

3. Use a mitre saw, or a mitre box, to cut the pipe squarely. If you do not own a mitre saw or mitre box, follow the steps in “Cutting a pipe without a mitre saw”.

4. Start by making a mark, 200mm from one end of the pipe & cutting the pipe along this mark. You will be left with a 200mm long piece of offcut pipe. Set it aside for later.

5. Repeat step 4 and put the second offcut piece aside as well.

6. Whenever you cut the pipe, remove any burr from the cut edges with sand paper or with a de-burring tool if you own one.

7. Use your tape measure to make a mark halfway along the length of the remaining piece of pipe.

8. Cut the pipe in half along the mark you made.

 

Drilling holes in the pipes

You must now drill equally spaced holes, all the way along the length of the pipes.

It is very important to ensure that the drilled holes are in a straight line, and perfectly at the top of the pipe.

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Follow the steps below to drill the holes:

There is often a line of printed text all along the pipes. If so, use this text as a reference to trace a straight line along the entire length of one side of the pipe. 

If no sprinted text on the pipe, follow the steps in “Marking the centre of a pipe” and then follow the steps below:

1. Tie the one end of the piece of string to one of the paper clips.

2. Bend the paper clip into a hook, and hook it over one edge of the pipe.

3. Bend the second paper clip into a hook as well and tie the other end of the string to it, just short of the other end of the pipe.

4. Now hook the this paper clip over the other end of the pipe, making sure the string is reasonably taught and straight.

5. Line the string up with the centre of the print along the pipe or line the paperclips up with the marks you made at either end, if you used the "Marking the centre..." method.

6. Use your marker to trace the line all along the string.

7. Now make a mark crossing the traced line, 100mm from one end of the pipe.

8. Move to the opposite end of the pipe, and make a mark 100mm from this end as well.

9. Make another mark, 180mm from the same end of the pipe.

10. Use your tape measure to measure the exact distance between the 180mm mark and the 100mm mark at the opposite end of the pipe. (If you started with a 6meter length of pipe, this distance should be approx. 2500mm or 250cm).

11. Divide your measured distance by 10. 10 spaces will result in 11 holes, approx.. 250mm apart.

12. Use your tape measure to make marks, all along the trace line, each spaced apart by the distance you calculated above. (250mm)

13. Secure the pipe by clamping it or by strapping it to a steady object before drilling the holes. Drilling into an unsupported pipe can damage the pipe or cause injury to yourself. Be careful.

14. Install the 76mm hole saw in your drill machine.

15. Line the drill centre up with the first mark which is 100mm from the pipe edge. (Drill a 5mm pilot hole if you have difficulty keeping the drill centre on the mark)

16. If you are using a hand drill, take care to hold the drill perpendicularly to the pipe while drilling.

17. Drill a hole through the one side of the pipe, but take care not to puncture through to the opposite inside surface of the pipe. (Keep the rotation speed of the drill moderate otherwise you may melt the PVC).

18. Line your drill centre up with the next mark and continue to drill all the holes in the same manner as above.

19. Before you drill the last hole, take care to support the drill whilst drilling the hole, as you will notice that it overlaps the previous hole, and some of the pipe surface under this hole has already been removed by the previous hole.

20. Once you have drilled the last hole, you will notice two pointy protrusions between the holes. You can optionally draw a line between the radii of the two adjacent holes on either side and use a jigsaw to cut them out, making an oval shape out of the last two holes. (This part will be covered up, so it isn't required to follow this step)

21. Make a mark, close to the edge, anywhere along the length of one of the 200mm long offcut pieces of pipe.

22. Wrap your tape measure around the circumference of the pipe, and starting at the mark you made, make another mark 60mm away, also close to the edge of the pipe.

23. Use the "Marking the centre of a pipe" method to make marks along the opposite edge of the pipe, corresponding to the previous two marks.

24. Clamp the 200mm offcut pipe securely and carefully cut along each of the two parallel lines until the 60mm piece drops out of the pipe. You now have a cover for the oval hole at one end of the pipe. Simply force it open slightly and slide it along the pipe to cove the hole.

25. Use sand paper or a de-burring tool to remove the burr from the drilled holes.

26. Repeat steps 1-25 to drill the holes in the 2nd length of pipe.

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Cutting the 75mm Pipe inserts

Follow the steps below to make the inserts:

I recommend that you use a mitre saw, preferably a power mitre saw to produce the inserts, as it will be very time consuming to produce them in any other way.

You will produce one insert for every 75mm hole that you drilled in the pipes (48).

 

NOTE - Be careful when cutting short pieces of pipe, especially with a power saw.

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1. Cut off the end of the 75mm pipe square if required.

2. Make a mark, 30mm from the edge, and cut a square piece off the pipe along the line.

3. Repeat step 2 to produce 48 pieces.

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Gluing the inserts into the 110mm pipes

 It is important to insert and glue the inserts perpendicular to the 110mm pipe.

Follow the steps below to achieve this:

1. Carefully insert one of the inserts into one of the drilled holes in the 110mm pipe. It may be a tight fit, but you can bend the insert a little in order to force it into the hole.

2. Position the insert inside the hole so that its top rim is flush with the top of the 110mm pipe along its length.

3. Use your tape measure or a ruler to ensure that the sides of the insert, protrude equal distances from the 110mm pipe on either side. 

4. Make small marks at the lowest points where the 75mm pipe meets the 110mm pipe on either side.

5. Now lift the insert up approx. 5mm.

6. Run a small bead of PVC glue right around the rim of the insert.

7. Slowly push the insert into the 110mm pipe until the edges of the insert are flush with the highest ends of the hols in the 110mm pipe, and the marks you made, line up with the lowest parts of the hole in the 110mm pipe.

8. Allow the glue to set for at least 30minutes.

9. You now have one insert that is squarely glued in place. You will now use this insert as a reference to fit the remaining inserts squarely. If you want to, you can follow steps 1 - 8 to fit more inserts along the pipe, or even all of them, but his is a very time consuming process and the steps below will speed it up.

10. Follow steps 1-2 to fit an insert into one of the holes.

11. Proceed with step 5-6.

12. Place a flat piece of wood over the square insert already glued and position it so that it also covers the insert you are fitting. Hold the wood firmly over the already glued insert and slowly push down on the newly glued insert. This will transfer the square alignment of the already glued insert to the newly glued insert.

13. Remove the wood and ensure that the insert is flush with the highest spots in the drilled hole in the 110mm pipe.

14. Repeat this process until all the inserts are glued in place. Follow steps 1 - 8 if you find that you are unable to glue the inserts in straight.

15. Wipe excess PVC glue from the surrounding area when gluing as the glue tends to discolour after a while. Take care not to move the inserts while the glue is still wet.

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Cutting a pipe without a mitre saw.

1. Join two sheets of photocopier paper squarely together, end-to-end, with cellophane or masking tape.

2. Wrap the paper firmly around the pipe, with one end of the paper close to the mark where you want to cut the pipe, making sure the two ends of the paper sheet meet perfectly. Use cellophane or masking tape to stick the ends of the paper together, forming the paper into a snug tube around the pipe.

3. Adjust the position of the paper so that it lines up perfectly with the halfway make you made, and trace the edge of the paper, all the way around the pipe. This line will be perfectly perpendicular to the length of the pipe.

4. Remove the paper and carefully cut along the line, all the way around the pipe, taking care not to deviate too much form the line.

5. Rotate the pipe as you cut through it so you can follow and stay on the line.

 

 

 

 

Marking the centre of a pipe.

1. Place the pipe on a level surface, or support it levelly between two trestles or chairs.

2. Place a marble or small ball close to the edge, inside the open end of the pipe.

3. Wait for it to stop moving and use your marker to make a mark around the edge of the pipe, exactly below the centre of the marble.

4. Repeat this step at the other end of the pipe, but take care not to move or rotate the pipe whilst marking it.

5. Once marked, rotate the pipe so that the marks are near the top.

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