2. Methods

2.1       Equipment list (divide into 4 categories)

Sensors
  • Ammonia sensor x1
  • Nitrate sensor x1
  • Dissolved Oxygen sensor x1
  • pH sensor x1
  • Salinity levels x1
  • Temperature sensor x1
  • Chloride sensor x1
  • Calcium chloride sensor (hardness of water) x1
  • Data loggers x3

Breeding system
  • Food timer x1
  • Cichlids fish food x1
  • Fish tank x1
  • Water pump x1
  • Air pump x1
  • Air tubes
  • pH + solution x1
  • pH - solution x1
  • Bacteria life solution x1

Hydroponics
  • Hydroponics tray x1
  • Board x1
  • Net pots x9
  • Butterhead lettuce seedlings x9
  • Leca beads x1 packet

Filter system
  • 1.25 litre plastic bottle x1
  • Bacteria cultivating balls 1 packet
  • Small pebbles
  • Filtering medium x1


2.2       Diagrams

Design 1





Design 2





2.3       Procedures

Fish tank
  1. Pour tap water into the fish tank and fill in 3/4 full.
  2. Submerge the water pump into the fish tank.
  3. Connect the water pump with the connectors using a water hose.
  4. Connect the connectors to the 1.25 litre bottle using a water hose.
  5. Switch on the water pump.
  6. Connect the oxygen pump to the fish tank using air pipes.
  7. Switch on the oxygen pump and turn the air pressure to high.
Hydroponics 
  1. Measure the diameter of each net pot (7.5cm), and cut 10 holes from the foam board accordingly.
  2. Put the 9 net pots into the holes that were cut out in the foam board and leave one empty.
  3. Place the foam board with the pots on top of a container.
  4. Drill a hole at a height of 7cm from the bottom of the container. (overflow method)
  5. Pour water into the container until it is 3/4 full.
  6. Tape a piece of string below the hole to guide the water into the fish tank.
  7. Wash away the soil from the butterhead lettuce seedlings’ roots.
  8. Put the butterhead lettuce into the net pots.
  9.  Fill up the net pots that have the butterhead lettuce with Leca beads to support it. 
Breeding system
  1. Put 10 tilapias into the fish tank.
  2. Feed the tilapias with the fish food. (3 spoons, 3 times per day)
Filter system
  1. Cut the bottom of a 1.25 litre bottle.
  2. Turn the bottle upside down.
  3. Poke two holes through the cap and cap the bottle.
  4. Pour the bacteria cultivating balls into the bottle.
  5. Pour pebbles on top of the bacteria cultivating balls.
  6. Place a filter medium on top of the pebbles.
  7. Poke a hole at the height of 14 cm from the bottom of the cap. (overflow method)
  8. Place the filter bottle above the empty hole in the foam board.
  9. Connect a water hose to the hole for the water to flow out into the tank.
Sensor system
  1. Place the chloride sensor into 1/2 of the depth of water to check the chlorine level.
  2. Turn on a data logger.
  3. Connect the chloride sensor to the data logger and observe the chlorine levels of the tap water in the fish tank over a few days. Fishes cannot survive in waters of high chlorine levels, therefore the water should have a chlorine level as low as possible before we put in the fishes.
  4. Put the nitrate and ammonia sensors into 1/2 of the depth of water in the fish tank.
  5. Connect the sensors to the data logger.
  6. We will not feed the fish for two days and observe for any changes in the ammonia level         and nitrate level. 
Instructions for usage of sensors

For Chloride, Ammonia, Nitrate, Salinity, Calcium chloride, pH sensors
  1. Recalibrate the sensors.
  2. Insert the tip of the sensor into the water.
  3. Connect the sensors to the data loggers for data collection. 
For Temperature Probe (does not require calibration)
  1. Insert the tip of the sensor into the water. 
For Dissolved Oxygen Sensor: 
  1. Remove the membrane cap from the tip of the probe.
  2. Using the pipet, pour 1 ml of the DO Electrode Filling Solution into the membrane cap.
  3. Carefully screw the cap back into the electrode.
  4. It is necessary to warm up the probe for 10 minutes before taking readings. To warm up the probe, leave it in the water and connect it to the data logger, and leave it running for 10 minutes.
Instructions for calibration of sensors
*Temperature Probe and Salinity probe does not require any calibration. 

For Calcium and Chloride sensors:
1. Wash the tip of the sensor thoroughly with tap water/deionised water.
2. Dry the sensor with a paper towel.
3. Connect the sensor to the data logger.
4. Switch to the calibration mode.  
5. Dip the sensor into the 1000 mg/L chloride/calcium solution.
6. Make sure that the ISE is not resting on the bottom of the container containing the solution.
7. Wait for 30 secs for the live voltage to stabilise.
8. Take out the sensor.
9. Wash the tip of the sensor with tap water/deionised water.
10. Wipe it dry with a paper towel. 
11. Enter the calibration route on the data logger. 
12. Dip the tip of the sensor into the 10 mg/L chloride/calcium solution.
13. Make sure that the ISE is not resting on the bottom of the container containing the solution.
14. Wait for 30 secs for the voltage to stabilise. 
15. Take out the sensor.
16. Wash the tip of the sensor with tap water/deionised water.
17. Wipe it dry with a paper towel. 

For Ammonium and Nitrate sensors:
1. Wash the tip of the sensor thoroughly with tap water/deionised water.
2. Dry the sensor with a paper towel.
3. Connect the sensor to the data logger.
4. Enter the calibration route on the data logger.  
5. Dip the sensor into the 100 mg/L ammonium/nitrate solution.
6. Make sure that the ISE is not resting on the bottom of the container containing the solution.
7. Wait for 30 secs for the live voltage to stabilise.
8. Take out the sensor.
9. Wash the tip of the sensor with tap water/deionised water.
10. Wipe it dry with a paper towel. 
11. Switch it to the calibration mode again. 
12. Dip the tip of the sensor into the 1 mg/L ammonium/nitrate solution.
13. Make sure that the ISE is not resting on the bottom of the container containing the solution.
14. Wait for 30 secs for the voltage to stabilise. 
15. Take out the sensor.
16. Wash the tip of the sensor with tap water/deionised water.
17. Wipe it dry with a paper towel.               
For pH sensor:
1. Wash the tip of the sensor thoroughly with tap water/deionised water.
2. Dry the sensor with a paper towel.
3. Connect the sensor to the data logger.
4. Enter the calibration route on the data logger.  
5. Dip the sensor into the pH 4 solution.
6. Make sure that the ISE is not resting on the bottom of the container containing the solution.
7. Wait for 30 secs for the live voltage to stabilise.
8. Take out the sensor.
9. Wash the tip of the sensor with tap water/deionised water.
10. Wipe it dry with a paper towel. 
11. Switch it to the calibration mode again. 
12. Dip the tip of the sensor into the pH 7 solution
13. Make sure that the ISE is not resting on the bottom of the container containing the solution.
14. Wait for 30 secs for the voltage to stabilise. 
15. Take out the sensor.
16. Wash the tip of the sensor with tap water/deionised water.
17. Wipe it dry with a paper towel. 

For Dissolved Oxygen Probe:
  1. Enter the calibration route for the data logger.
  2. First Calibration Point: Place the tip of the probe into the Sodium Sulfite Calibration Solution. Insert the probe into the solution at an angle.
  3. When the voltage displayed reading stabilises, enter 0 (the known dissolved oxygen value in mg/L)
First Calibration Point 
  1. Second Calibration Point: Rinse the probe with distilled and gently blot dry.
  2. Unscrew the lid of the calibration bottle provided with the probe. Slide the lid and the grommet about 1/2 inch onto the probe body.
  3. Add water to the bottle to a depth of about 1/4 inch and screw the bottle into the cap, as shown. Important: Do not touch the membrane or get it wet during this step. Keep the probe in this position for about a minute.
  4. When the displayed voltage reading stabilises, enter the correct staurated dissolved oxygen value in (mg/L) using the current barometric pressure and air temperature values.
Second Calibration Point

Approximate Calibration Voltages 
  1. Ammonia sensor has a 2.1 voltage for high solution (100 mg/L) and 1.3 voltage for the low solution (1 mg/L)
  2. Calcium sensor has a voltage of 1.9 voltage for high solution (1000 mg/L) and 1.5 voltage for low solution (10 mg/L) 
  3. Chloride sensor has a voltage of 2.0 for high solution (1000 mg/L) and 2.8 voltage for low solution (10 mg/L)
  4. Nitrate sensor has a voltage of 1.6 for high solution (100 mg/L) and 2.4 voltage for low solution (1 mg/L)

2.4       Risk Assessment and Management

Severity Column 

Source: (Workplace Safety Health Council, 2012)

Likelihood Column
Source: (Workplace Safety Health Council, 2012)


Classification of Risk
Source: (Workplace Safety Health Council, 2012)


Risk Matrix  (Risk Evaluation)
Source: (Workplace Safety Health Council, 2012)
  1. Large amounts of water is used, and the fish tank is near the socket. The students may have a likelihood of getting an electric shock if spillages of water occur. This risk has a likelihood of 4 (frequent) as students are commonly exposed to this, every science lesson, which is 4 times a week. The severity of the risk is 4 (major) as an electric shock may result to burns, bruises and even death. Classification of risk is 6 (medium risk) which is still tolerable, but there must be careful evaluation and management of the risk. Students can move the fish tank away from the sockets.
  2. Using a pen knife to cut the plastic bottle and the styrofoam board for hydroponics board. The students may have a possibility of cutting themselves. This risk has a likelihood of 2 (remote), as there is only one styrofoam that needs to be cut. The severity of the risk is 2 (minor), of which is minor cuts. Classification of risk is 4 (low risk) which is acceptable, but frequent review and monitoring of hazards are required. Students should wear safety goggles and perform this under the supervision of an adult.
  3. Using the hot glue gun to seal up the hole in the tray. The students may have a possibility of burning themselves. This risk has a likelihood of 1 (rare). The severity of the risk is 2 (minor), of which is burns. Classification of risk is 2 (low risk) which is acceptable, but frequent review and monitoring of hazards are required. Students should perform this under the supervision of an adult.

2.5       Data Analysis
  1. Using the sensors, we will record down the water parameters of the water in the fish tank. We will dip all the sensors into the water in the fish tank and then connect them to the dataloggers. The dataloggers will be record down the data of different water parameters over a period of time and then, we will export the data into the Logger Pro 3 application into our learning devices. After that, we will analyse the data and the graphs. Over time, we will find that our ammonia level has decreased and our nitrate levels has increased, which shows a sign of the experiment working well. 
  2. Measure the length of the fishes, height of the plants and number of leaves at the start of the experiment. Every Monday, Wednesday and Friday, we will do the same measurements and plot graphs using the data collected. Two separate graphs for fishes and the plants. Graph 1, Y axis will be the length of fishes (cm) and X axis will be the number of days. Graph 2, height of the plants (cm) and number of leaves, while X axis will be the number of days. Looking at the growth and rates of the fishes and plants, and that they survive, then we can determine if the experiment is working well. 
  3. We also can use video clips to explain our system and to show how it works. Take a video of the bell siphon working. We can also plot a graph to show the height of water level in the hydroponics tray against the time, with Y axis for the height (cm) and X axis for the time (minutes). 

No comments:

Post a Comment