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Mini Hydroponic System with a Attiny10 Controller

I am building a desktop-scale mini hydroponic system with almost completely 3D printed parts and an Attiny10 controller board.

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I am interested in building a small-scale hydroponic system that can also fit on my desktop to observe closely its performance in growing a plant. I had no previous experience in hydroponics so, I started searching on the internet and decided to go with the flood and drain system. Since it would be an experimental setup, I had to think about my budget to save money. I thought it would be great if the entire planting pot could be 3D printed.

I have also prototyped and designed a controller board that is squeezing Attiny10 features. I actually love to work with Attiny10 since it is easy to learn and work with. I think it is definitely a form fit for this project.

These days, I am interested in building a small-scale hydroponic system that can also fit on my desktop to observe closely its performance in growing a plant. I had no previous experience in hydroponics so, I started searching on the internet and decided to go with the flood and drain system. Since it would be an experimental setup, I had to think about my budget to save money. I thought it would be great if the entire planting pot could be 3D printed. I would also definitely need a water pump to pump the nutrient solution. It would be great if the pump could be powered by a USB charger. So I came up with these requirements.

It should be: 

- small to fit on a desktop.

- cost-efficient to save money.

- a resemblance to the actual system, which can also be scalable.

- powered by a USB charger or maybe a power bank. Let me rephrase this as low power.

- preferred to be 3D printed.

How will it work?

In summary, the system will work as follows. There will be two tanks piped together. The first tank will hold the plant; the second will be the reservoir which will contain the nutritious water. There will be a controller which will track the time. For example, once every hour during the day time controller will pump the nutritious water from the reservoir to the first tank containing the growing plant and will flood the tank. After and during the flooding, water will be drained back into the reservoir tank. The controller will follow a different watering scheme for day and night time. Therefore, a light sensor will be utilized by the controller.

Discussions on advantages and disadvantages

As far as I have searched from the internet and having watched several hours of YouTube videos, I can list several advantages and disadvantages of this system over other hydroponic systems. Here you can find a brief list of mine.

First, advantages:

- Simple and easy to operate.

- Low power to operate. This is because the pump is only operated a few times during the day.

- Enables enough oxygenation of the roots

- Low probability of fungal growth

- Maintains a lower root temperature

Disadvantages:

- Requires separated tanks for plants and nutritious water

- Probability of low dissolved oxygen in the nutritious water

- Probability of algae growth due to the low dissolved oxygen

Designing the system

Before doing anything, first I searched for a pump on the Internet and I found this:

Pump
5V pump

There were some variations of this pump, but the cheapest one was this which I could manage to buy.

Some listed properties of the pump are:

- 80 to 120 Liter/hour flow rate

- 2.5-6 V DC operating voltage

- 130-220 mA operating current

- 40-110 cm hydraulic head

- 56mm length, 24mm diameter

- suitable for water

After a few hours spent on modeling, I have designed this planting medium. This design consists of two tanks which are top and bottom. The bottom tank preserves nutritious water and pumps, while the top tank contains clay pebbles and the plant. A form of clay which is called "hydroton" can be used at the top tank, or cocopeat can also be used instead.

Mini hydroponic growing medium
Mini hydroponic growing medium

Water and air pipes:

To equalize the reservoir pressure with the outside pressure while the pump is operating, we need a small air pipe whose one end is connected to the reservoir and the other end is open in the air. This small pipe also serves a second function. Although it is not guaranteed to work if the growing media is over-flooded with water, this pipe can drain the excess water to the reservoir. The second and the larger pipe is the water pipe which is directly connected to the pump. At one end of this water pipe, there is an elbow connected to direct and adapt the dimension of the pump outlet. At the other end of the tube is a chimney that is used to keep pressurized water flowing downwards into the growing medium rather than spouting it.

Pipes
Pipes

Dimensions:...

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Attiny10.zip

Gerber files

x-zip-compressed - 16.56 kB - 09/22/2021 at 18:08

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Attiny10.pdf

Schematics and board drawings

Adobe Portable Document Format - 317.84 kB - 09/22/2021 at 18:08

Preview
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elbow.stl

3D Print file

Standard Tesselated Geometry - 540.80 kB - 09/22/2021 at 18:06

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wire mesh.stl

3D Print file

Standard Tesselated Geometry - 113.75 kB - 09/22/2021 at 18:06

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Top.stl

3D Print file - growing medium

Standard Tesselated Geometry - 73.42 kB - 09/22/2021 at 18:06

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  • 1 × Pump Silent Submersible Pump

  • 1
    Assembly:

    As I have printed top and bottom tanks in so-called "vase mode" this has some drawbacks. Since vase mode gradually and continuously prints the part without moving the print head, it is only possible to print the surface of the model. For this reason, parts have to be assembled piece by piece after printing, since they cannot be printed all at once. Here are some tips according to my experience. First, I marked the drilling points. After marking, I used a 3mm drill bit and drilled the holes slowly and carefully without applying excess pressure on the drill from the bottom face of the growing tank. When the holes are open, reverse the tank upside down and then use a piece of wood to support the bottom face before widening the holes with a larger drill bit. Here, I used 6mm and 10mm drill bits to widen the ventilation hole and pump outlet piping holes. The 3 holes for drainage in the center are left as 3mm without widening. Check and practice the pipes on the holes and use a file if necessary to deburring the holes. Drilling steps are given in the following photo.

    The ventilation pipe is also printed in vase mode, but this time it is printed with raster. This enables gluing this pipe to the growing tank. This is shown in the following photo. The outlet pipe of the pump can be left without gluing only with a tight-fitting. In the following photo, the motor and the pipes are positioned on the growing tank. The pump cable will be routed through the gap on the sidewall. Press and fit the chimney properly to the end of the outlet pipe.

  • 2
    Water tightening the reservoir tank:

    As I have mentioned earlier, I printed all the parts in a 3D printer with PLA. As 3D printer users may already have experienced, printed parts will most probably leak after a while. So to make it watertight I printed all parts not only in vase mode, but also covered the interior of the reservoir tank with a thin film of a food-safe film. Placing and covering the interior of the tank with a film is a little bit tricky. I have given a demonstration below describing how to install this film supported with photos, but for now, I will just go over some major points. First, the food-safe film should be roughly laid inside of the reservoir tank, and then a 3D printed rigid part should be pressed on top of it. This will help to stretch the film at the bottom and protects the pump from sucking the thin film. Then the sides of the film should be bent outside on the edges of the reservoir. After that, the upper growing medium together with the motor and pipes should be slid into the reservoir. As given in the upper dimensional drawing in the A-A section, the upper tank slides and fits into the bottom tank. Excess film protruding between the tanks should be cut with the help of a utility knife. These details are given in the following photos.

  • 3
    Water-tightness test:

    Here is a quick test for the water-tightness of the reservoir and growing tank. Add half a glass of water or maybe less from the top; wait until the water is completely drained to the reservoir tank. Then start the pump by applying 5 volts to the ends. If the pump does not start, do not worry. This may be because there can be air trapped inside the pump's impeller. This can be easily fixed by removing the chimney from the outlet pipe and adding extra water from the top. You can watch my test results in the following short video below.

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