4. Discussion

4.1       Key Findings


When a large amount of tap water was first introduced into the tank, the chlorine level increased drastically. Water had to be stored in a container for at least a day before it can be transferred into the tank. Another method was to introduce smaller amounts of water at intervals.


The ammonia level had increased after introducing the fishes into the fish tank. The fishes were not fed at that time.


After the filter was implemented into the system, the ammonia level increased slightly before remaining constant. The nitrate level also increased.


4.2       Explanation of Key Findings


High chlorine level in the water is harmful to the fishes’ health as it reacts with living tissues in fishes and caused it to die. Fish gills are exposed directly to the water and dead cells in the gills can result to respiratory difficulty and even death. (Lewbart, 2013) During the start of the experiment, we let the water sit in the tank for a few days. Chlorine has high volatility, causing it to dissipate from water as gas easily. (National Response Team, 2011). After putting it for 1 week, the chlorine level has significantly decreased and is now safe to put the fishes into the water.


Un-ionized ammonia, NH3 is the form that is harmful to the fishes. (Environment Canada, 2013) The fishes excrete waste and it is broken down and released into ammonia. After putting in the fishes and not feeding for three days, we observed that the ammonia level has increased, due to the fishes excreting waste.


Filter in the fish tank will trap the solid waste and also provide as a medium for bacteria cultivation, due to its large surface area. Bacteria will then convert the ammonia (NH3) into nitrates (NO3-) in the process of nitrification. We were able to construct a aquaponics system with as little and easiest to get materials, such as the fish tank; containers; wood for the shelves, and equipment such as saws, drills and hot glue guns. Our system incorporates the idea of an automated feeding system for the fishes, which is the food timer and a automatic draining water system for the container with the plants, which is the bell siphon. Wastage of water is negligible as all the water is being recycled throughout the entire system. The plants are growing fast and healthily, and the fishes are also increasing in size over the days. The amount of water loss is minimal as the water is always circulating throughout the entire system, testimony that we are able to save water efficiently as well as rear fish and grow plants. The plants are also edible, which makes the produce more sought after.

4.3       Evaluation of Engineering Goals

We were able to construct a aquaponics system with as little and easiest to get materials, such as the fish tank; containers; wood for the shelves, and equipment such as saws, drills and hot glue guns. Our system incorporates the idea of an automated feeding system for the fishes, which is the food timer and a automatic draining water system for the container with the plants, which is the bell siphon. Wastage of water is negligible as all the water is being recycled throughout the entire system. The plants are growing fast and healthily, and the fishes are also increasing in size over the days. The amount of water loss is minimal as the water is always circulating throughout the entire system, testimony that we are able to save water efficiently as well as rear fish and grow plants. The plants are also edible, which makes the produce more sought after.

4.4       Areas for Improvement


1st Design

Filter

Top layer: Filter medium
Second layer: Small pebbles
Third layer: Black bacteria balls

Hydroponics Tray

Problems

1. Black bacteria balls are used to cultivate bacteria, which converts ammonia into nitrates.  Nitrates are essential for healthy plants growth. The water level in the filter must be higher than the level of black bacteria balls, in order for cultivation of bacteria to take place. However, the output of the water was faster than the input of the water, causing the water to flow out of the filter too quickly, the water flow was hence inconsistent. Therefore there is not enough time for the cultivation of bacteria, which results in a low nitrate level, causing the plants to die.

2. Fishes’ waste get trapped and accumulated in the water pipe that is transporting water up into the hydroponics tray. Over a period of time, it blocked the pipe, and impeded the flow of water, which affects the output of the water.

3. The filter medium, on the very top layer, traps the fishes’ waste and gets dirty very often. There is a need to change it every 3 to 4 days, which is very problematic. It is also not effective in filtering out the fishes’ waste.

4. The board is not waterproof, therefore any spillages or in contact with water, will result it to soften. Therefore, it is too weak to support the net pots containing the 8 plants.

5. Water in the hydroponics tray remain stagnant as the water flows out through an overflow hole at the other end of the container. Fishes’ waste that is not filtered out from the filter gets collected and sink at the bottom of the tray, causing the water to turn murky.


Solutions

1. Change to a submersible filter that filters the water within the tank, so that when water is pumped up into the hydroponics try using another water pump, the pipe connecting to it will not be accumulated with fishes’ waste and get stuck.

2. Build a bell siphon to release the water out of the hydroponics tray.

3. Use a thicker styrofoam board, which is waterproof.

2nd Design

eZ Filter

Pump to draw water from top and bottom of the filter.
Flow rate of 600L/H

Divided into 3 compartments:
White wool (mechanical filter) to trap large dirt particles
Activated carbon (chemical filter) to remove chemical impurities, odour, colouration
Bio sponge (biological filter) to cultivate bacteria and remove ammonia effectively



Bell Siphon


The purpose of the bell siphon is to flood the hydroponics tray with nutrient rich water and to draw oxygen into the tray.

As the water level rises in the hydroponics tray, water flows into the bell, through the teeth at the bottom. When the water level in the bell reaches above the height of the standpipe, the drain begins to fill, a siphon is created. Most of the water in the hydroponics tray is then drained out by the siphon until the water level reaches the height of the teeth and tip of the pipe, at the same time sucking air down around the roots and oxygenating everything. Air is then forced through the pipe, stopping the siphon process.  The hydroponics tray then continues to fill up water and the cycle repeats itself.


Height of the standpipe is the maximum depth of water in the hydroponics tray.



Final Design


Problems
1. The tank must be filled up with water till the brim, as the pump, located at the top of the filter, needs to be submerged, in order for it to work. However, there is no space for the hydroponics tray to rest on top of the fish tank, therefore a shelf is designed to hold the hydroponics tray.

2. The hydroponics tray is too short for the bell siphon.

3. As the pipe connecting to the bell siphon is in the centre of the hydroponics tray, a hole must be drilled at the centre of the wood, which is very troublesome.

Solutions
1. Get a plastic tray with a taller height.

2. We decided to use two shelves to support the hydroponics tray, so that it is more stable and the pipe, connecting to the bell siphon, can be placed between the both shelves.

3. When a large amount of tap water was first introduced into the tank, the chlorine level increased drastically. Water had to be stored in a container for at least a day before it can be transferred into the tank. Another method was to introduce smaller amounts of water at intervals.


4. The ammonia level had increased after introducing the fishes into the fish tank. The fishes were not fed at that time.


5. After the filter was implemented into the system, the ammonia level increased slightly before remaining constant. The nitrate level also increased.


4.2       Explanation of Key Findings


High chlorine level in the water is harmful to the fishes’ health as it reacts with living tissues in fishes and caused it to die. Fish gills are exposed directly to the water and dead cells in the gills can result to respiratory difficulty and even death. (Lewbart, 2013) During the start of the experiment, we let the water sit in the tank for a few days. Chlorine has high volatility, causing it to dissipate from water as gas easily. (National Response Team, 2011). After putting it for 1 week, the chlorine level has significantly decreased and is now safe to put the fishes into the water.


Un-ionized ammonia, NH3 is the form that is harmful to the fishes. (Environment Canada, 2013) The fishes excrete waste and it is broken down and released into ammonia. After putting in the fishes and not feeding for three days, we observed that the ammonia level has increased, due to the fishes excreting waste.


Filter in the fish tank will trap the solid waste and also provide as a medium for bacteria cultivation, due to its large surface area. Bacteria will then convert the ammonia (NH3) into nitrates (NO3-) in the process of nitrification.


4.4       Areas for Improvement


1st Design

Filter

Top layer: Filter medium
Second layer: Small pebbles
Third layer: Black bacteria balls

Hydroponics Tray

Problems

1. Black bacteria balls are used to cultivate bacteria, which converts ammonia into nitrates.  Nitrates are essential for healthy plants growth. The water level in the filter must be higher than the level of black bacteria balls, in order for cultivation of bacteria to take place. However, the output of the water was faster than the input of the water, causing the water to flow out of the filter too quickly, the water flow was hence inconsistent. Therefore there is not enough time for the cultivation of bacteria, which results in a low nitrate level, causing the plants to die.

2. Fishes’ waste get trapped and accumulated in the water pipe that is transporting water up into the hydroponics tray. Over a period of time, it blocked the pipe, and impeded the flow of water, which affects the output of the water.

3. The filter medium, on the very top layer, traps the fishes’ waste and gets dirty very often. There is a need to change it every 3 to 4 days, which is very problematic. It is also not effective in filtering out the fishes’ waste.

4. The board is not waterproof, therefore any spillages or in contact with water, will result it to soften. Therefore, it is too weak to support the net pots containing the 8 plants.

5. Water in the hydroponics tray remain stagnant as the water flows out through an overflow hole at the other end of the container. Fishes’ waste that is not filtered out from the filter gets collected and sink at the bottom of the tray, causing the water to turn murky.


Solutions

1. Change to a submersible filter that filters the water within the tank, so that when water is pumped up into the hydroponics try using another water pump, the pipe connecting to it will not be accumulated with fishes’ waste and get stuck.

2. Build a bell siphon to release the water out of the hydroponics tray.

3. Use a thicker styrofoam board, which is waterproof.

2nd Design

eZ Filter

Pump to draw water from top and bottom of the filter.
Flow rate of 600L/H

Divided into 3 compartments:
White wool (mechanical filter) to trap large dirt particles
Activated carbon (chemical filter) to remove chemical impurities, odour, colouration
Bio sponge (biological filter) to cultivate bacteria and remove ammonia effectively


Bell Siphon


The purpose of the bell siphon is to flood the hydroponics tray with nutrient rich water and to draw oxygen into the tray.

As the water level rises in the hydroponics tray, water flows into the bell, through the teeth at the bottom. When the water level in the bell reaches above the height of the standpipe, the drain begins to fill, a siphon is created. Most of the water in the hydroponics tray is then drained out by the siphon until the water level reaches the height of the teeth and tip of the pipe, at the same time sucking air down around the roots and oxygenating everything. Air is then forced through the pipe, stopping the siphon process.  The hydroponics tray then continues to fill up water and the cycle repeats itself.


Height of the standpipe is the maximum depth of water in the hydroponics tray.




Final Design


Problems
1. The tank must be filled up with water till the brim, as the pump, located at the top of the filter, needs to be submerged, in order for it to work. However, there is no space for the hydroponics tray to rest on top of the fish tank, therefore a shelf is designed to hold the hydroponics tray.

2. The hydroponics tray is too short for the bell siphon.

3. As the pipe connecting to the bell siphon is in the centre of the hydroponics tray, a hole must be drilled at the centre of the wood, which is very troublesome.

Solutions
1. Get a plastic tray with a taller height.

2. We decided to use two shelves to support the hydroponics tray, so that it is more stable and the pipe, connecting to the bell siphon, can be placed between the both shelves.

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