4. Discussion

4. Discussion

4.1 Key findings

The flow rate of the water (from the top layer to the lower layer- fish area) was relatively fast, achieving a timing of 3.8 seconds when it travelled from the top of the tank to the bottom (via the pipes as seen in Figure 3.1) . This means that the water can be transported efficiently and effectively, catering to the needs of survival for the fishes and the plants. 

The temperature sensor is also able to work with the relay system and because of the hot-glue on it, it is able to penetrate through water without short-circuiting the entire system. The temperature is constant throughout of 24.5 degrees Celsius and the fan automatically turns on to cool the water, reducing it to 24 degrees Celsius. 

Plants growing upwards is an indicator that it is taking in water and that it is growing towards the LED lights, photosynthesising.  

We have found that the plants are surviving in our system. However, there are plants that are withering. We have also found that the soil constant has a better growth rate than the plants cultivated in the vertical garden. Other than that, the fish has survived with the plants and most of the plants are growing healthily due to the ammonia produced by the fishes. 


4.2 Explanation of key findings

This could be so due to the fact that the plants were upright, hence the water is pulled down with the highest gravitational pull possible. Furthermore, the pump is turned on for 30 minutes each time, hence the time given for the absorption of water by the plants is sufficient and that they will efficiently absorb the nutrient-infused water.

The results shown mean that the plants would have sufficient time to absorb the water, allowing them to take in what is required and that the fish’s faeces, which contain ammonia, act as fertiliser to the plant, allowing them to grow healthily.

Over a period of 4 days, we have found out that majority of the plants in the Aquaponics system are growing, with the exception of one of them that is wilting. This could be caused by a lack of oxygen to the roots or overcrowding because of the insufficient light the LED lights provide. Nutrients absorbed by a single stalk would then be not as abundant as compared to other sponges with fewer stalks. The soil constant also has a better growth rate than the vertical garden. This may be caused by the easily available nutrients present in the soil. This would then cause stunted growth, as seen when comparing the vertical garden and the soil constant. The plants on the uppermost row are seen to be growing, with some growing better than those found in the middle or the bottom.

The temperature sensor from the Arduino is used to control the temperature of the water. The temperature sensor is connected to a relay system which is then connected to a fan which acts as our chiller. To activate the fan, we did some coding on the Arduino and uploaded it to the Arduino. The temperature sensor was placed into the water and if the temperature of the water is above 24˚C, the fan will be activated. When the temperature is below 23˚C, the fan will be turned off. The temperature is optimal for the fish to survive, ensuring a great harvest at the end of the project. 

4.3 Evaluation of engineering goals

We are able to construct a temperature-controlled Aquaponics system with minimal and conveniently available resources, such as Arduino, fans, relay systems and temperature sensors. It also incorporates automation of lighting through the LED lights on the system.  Wastage of water is negligible as all the water is reused due to it being filtered to the various parts of the tank. The current design takes up an area of only 678cm2. The plants are also growing similarly to those growing within soil, as seen with the soil constant. It can be placed indoors, with protection from the elements. It can fit on a tabletop, testimony that it takes up little space and land compared to conventional methods such as horizontal farming etc. 

The temperature sensor system (connected with the Arduino and fan) also allows us to cool the temperature easily, ensuring the survival of the fish and plants. 

4.4 Areas for improvement

Our system has a flaw which may affect the growth of our fishes. The fan, also known as the chiller in this case is unable to cool down the water as effectively as a chiller. Thus, it would take about 10 to 15 minutes for the water to cool down, risking the lives of the fishes. Precautions have to be made in order to allow the circuit to go well, keeping the fish alive, as well as maintaining healthy plants. 

We are unable to measure the water in the tank currently, and we are only using an estimate to refill the amount of water. We could improve the system by placing a sensor/detector to monitor the water level of the tank, to keep a constant amount of water at a time. This also allows us to add an exact amount of nutrient solution into the water to ensure there is no excess or lack of nutrients which may potentially stunt the growth of the plants.


We are currently using a pump that occasionally does not keep a constant flow through the pipes. We could improve on this by purchasing a better pump that will help to ensure that each outlet will receive a constant/steady and equal flow of water. Problems we face now include excessive bubbles in the water and irregular flow.

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