Plant Growth in Aquaponic System through Comparison of Different ...

Plant Growth in Aquaponic System through Comparison of Different Plant Media
Jessica Mader
Senior Honors Project
Submitted in partial fulfillment of the graduation requirements
of the Westover Honors Program
Westover Honors Program
April, 2012
Dr. Thomas Shahady
Dr. Nancy Cowden
Dr. Priscilla Gannicott

Abstract
Aquaponics is a form of sustainable agriculture that combines crop and fish cultivation into a
water re-circulation system. Water containing fish waste is pumped to the plants, where nutrient
water is absorbed and utilized for plant growth. Alternatively, plants provide filtering of the
water of excess nutrients that can be toxic to the fish. This experiment tested two food crops
(lettuce and radish) grown in three different medias (soil, coconut fiber, gravel) in two separate
aquaponics systems (Nutrient Film Technique (NFT) and Floating Raft (FR)) to determine which
media maximized plant growth in both systems. Each plant was planted and replicated in each
pot (3X) and differing media (3X) as seed and grown for 8 weeks (NFT) and 5 weeks (FR).
Growth rates were measured by recording heights weekly and biomass (mg) at the end of the
experiment. Both lettuce and radishes had the greatest growth in soil in both systems. I believe
soil is the most effective because it supplies the plants with maximum water soil without
becoming overly saturated.
Introduction
Aquaponics is a form of sustainable agriculture that combines fish and plants in a closed
re-circulating system. Aquaponics is considered a form of sustainable agriculture because it uses
non-renewable resources and on-farm resources efficiently while still sustaining the economic
viability of the farm (Sustainable Agriculture: Definitions and Terms). Unlike traditional
farming, in an aquaponic system there is a constant flow of water and more constant supply of
nutrients for the plants. The waste created by the fish provides necessary nutrients for the plants
while nutrient uptake by the plants improves the water quality for the fish (Rakocy, 1989). A
separate biofilter is not needed because the plants act as a water filter when they absorb the
excess nutrients that can otherwise become toxic to the fish if too many harmful compounds
build up. Fish release ammonia through their waste, and high levels of this waste product can be
toxic to the fish, however these levels can be reduced through the process of nitrification.
Nitrifying bacteria convert ammonia to nitrite, then nitrate, a form of nitrogen that can be utilized
by plants. Thus, when the water returns to the fish tanks, nitrogen levels are tolerable for the fish
(Rakocy et al., 2006). The goal in using an aquaponic system is to increase production while

minimizing nutrient inputs and the consumption of water. The plants act as a filter for the water,
which minimizes total consumption of water throughout the growing season because it is
continually recycled throughout the system and does not need to be replaced with new, clean
water.
There are many different variations of aquaponic systems. The Nutrient Film Technique,
or NFT, uses a continuous flow of a thin layer, or film of water to deliver nutrients to the plants
(Figure 1). The plants are placed on a trough and a thin layer of water is pumped to the trough
and a continuous supply of nutrients is provided for the plants (Rakocy, 1999). The media in
which the plants are grown absorb the water as it flows down the trough and delivers it to the
plant roots (Rakocy, 1999). The water that is not absorbed by the media is returned to the fish
tanks with more tolerable levels of nutrients that will not kill the fish. Some water is lost due to
transpiration and evaporation at the leaf surface.

Figure 1 – NFT System Utilized at Lynchburg Grows in Lynchburg, Virginia. Water from the
bottom trough is pumped up to the upper two levels, where a thin layer of water flows down and
returns back to the bottom trough on the opposite side.
Another aquaponics variation is the floating raft technique (Figure 2). This system
requires troughs with a minimum of a foot of water. A “raft”-like structure containing individual
pots with the designated media float on the water so roots grow directly into the water. Seedlings
can be started in pots out of the system and after they germinated, are placed in the raft’s net pots
or started directly in the rafts in the troughs. This system provides maximum exposure of roots to
the nutrient-filled water. This system is ideal for cultivation of leafy greens or other types of
vegetables (Rakocy et al., 2006). This system does leave roots vulnerable to damage by aquatic
organisms, such as zooplankton or bacteria (Rakocy et al., 2006).
Figure 2 – Floating Raft System Utilized at Lynchburg Grows in Lynchburg, Virginia. The water
from the bottom trough is pumped up to the upper troughs through a pipe. The water enters at
one corner and drains out of the opposite corner.

There are many different medias in which to grow plants, and each has advantages and
disadvantages. The medias used in this experiment were gravel, soil, and coconut fiber. Gravel
has a large surface area for bacteria to grow and perform nitrification. Also, the composition the
gravel itself can provide some nutrients for plants as the water weathers the rock, for example
calcium can be released as the gravel reacts with acid produced during nitrification (Rakocy et
al., 2006). A disadvantage is that the gravel retains very little water. Soil has the ability to supply
the plants with enough water without becoming overly saturated. Because soil is composed of
smaller grain sizes compared to gravel, it is able to retain some water while the excess drains out.
There are also pore spaces that provide the plant roots with air (McCauley et al., 2005). Soil
naturally contains nutrients, but does not always contain enough for healthy plant growth and it
can be depleted of nutrients as the plant grows. Coconut fiber is made from the husk of a
coconut. It is highly absorbent material but it does not contain abundant nutrients. The different
medias provide surface area for bacteria to grow and perform nitrification, and capture solids
before they reach the plant roots (Rakocy et al., 2006). A good medium for plant growth creates
a nutrient pool around the plant roots and provides adequate air space for respiration (Sikawa,
2010).
There are a total of 18 essential nutrients for maximum plant growth. The three
macronutrients are carbon, oxygen, and hydrogen, which are supplied by the water and carbon
dioxide gas. Other macronutrients provided by the nutrient filled water include nitrogen,
potassium, calcium, magnesium, phosphorus, and sulfur. The remaining nutrients are
micronutrients. A balance of all these nutrients provides for optimal plant growth (Rakocy et al.,
2006).

ADD PARAGRAPH: kind of plants that are grown in hydroponics, indicate that the same
plants will work in aquaponics
Radishes are edible members of the Brassicaceae (Figure 3). Radishes require even and
moderate to heavy watering and prefer full sun, but can tolerate partial shade (Denckia, 2003).
They require low levels of nitrogen, phosphorus, and potassium. They do best in cool, moist soil
and a pH between 6.0 and 7.0. Radishes germinate between 4 to 12 days.
Figure 3 – Radish plant grown in soil in the NFT system at 7 weeks.
Lettuce belongs to the Asteraceae (Figure 4). It does not require a lot of water, but it does
need moderate water consistently and, like radishes, prefers full sun, but can tolerate partial
shade (Denckia, 2003). Lettuce plants require high levels of nitrogen, phosphorus, and
potassium. The lettuce plant has a relatively shallow, compact root system that does not absorb
nutrients and moisture from the soil very efficiently. The optimum soil pH is between 6.5 and
7.0. The plant typically germinates within 7 to 14 days.

Figure 4 – Lettuce plant grown in the soil in the NFT system at 7 weeks.
In this experiment, lettuce and radishes were grown in three different media to determine
which media=um resulted in the greatest plant performance. Each plant type was grown in soil,
gravel, and coconut fiber as different treatments. Also, two different aquaponic systems were
used; the NFT and the floating raft system. The goal for this experiment was to determine which
crop and which medium yielded the greatest growth performance.
Methods
Study Site
This experiment was conducted at Lynchburg Grows, located in Lynchburg, VA,
(3724’13’’N 7910’12’’W), is an urban farm that practices sustainable agriculture techniques.
There are a total of nine greenhouses with one dedicated to aquaponics. The construction of the
Nutrient Film Technique system was completed in September of 2011 and the construction of the
floating raft system was completed in October of 2011.

Experimental Design
Many different types of plants can be grown in an aquaponic system. The crops chosen
for this experiment needed to be suited for growing in the late summer/early fall. They also
needed to grow quickly so that growth data could be collected. Lettuce and radishes were two
crops that were suitable for this experiment. Lettuce is a suitable crop because it grows in short
periods of time and produce few pest problems (Rakocy et al., 2006). Radishes germinate
quickly and require low levels of nutrients. Lynchburg Grows provided the seeds for each plant.
Lynchburg Grows could easily continue growing this crops in the aquaponic system and sell
them for profit if we determine an aquaponic system that worked best.
Lynchburg Grows provided all the seeds, pots, and media for the project. In the NFT,
radish and lettuce were planted from seeds. For each crop, three seeds of one type of plant were
planted in one pot and seven pots were completed for each of the three media, for a total of 21
seeds per medium per plant type. A thin layer of soil was placed only on the top of the gravel to
act as a bed to hold the seed before it germinated. The pots were labeled and randomly arranged
by a fellow student and I distributing them along the top trough. They were planted on
September 12, 2011. (Variety of each plant, original source of seeds- where did LG get them)
In the floating raft system, eight holes were cut in a styrofoam board where small pots
were placed and the pots extended 2 inches into the water. This was done to four styrofoam
boards. Radishes and lettuce seeds were planted in the soil, coconut fiber and gravel. There were
a total pots, each with 2 seeds, for each treatment. The treatments were randomly arranged by
numbering the empty pots, making a list of all the treatments, drawing numbers out of a pot, and
going down the list assigning pot numbers to the treatments. All the treatments were listed, a

number that corresponded to a pot on the raft was drawn from a pot, and that number was
assigned to the treatment next on the list. Two pots were left empty in order to have an equal
number of pots per treatment. All plants were planted on October 3, 2011. (Pot size- internal
volume- how much growing media was available to the plants)
Two hundred channel catfish were added to the NFT and the same number to the floating
raft system on October 26 (Figure 5). This date for stocking was after my planting date due to
availability of fish. Channel catfish were obtained from a hatchery in eastern Virginia, were
pellet trained and a good choice for this type of system (Shahady personal commentation). While
the fish are an important component of an aquaponic system, this project was designed to study
plants thus any discussion of fish in this system is a separate study. (where were the fish
obtained from- what hatchery, age/size)
(picture to come)
Figure 5 – Channel Catfish stocked into the Aquaponic units.
Type of system
Construction of the system was based on similar units in use at Growing Power Inc.
(where is it located) (Will Allen personal communication, 2010). The types of systems used
were the nutrient film technique (NFT) and floating raft. In the NFT, a thin layer of constantly
flowing water provides a continuous supply of water, nutrients, and oxygen. In the floating raft
system, plants roots grow directly into a container of water. The rafts provide optimum root
exposure to the nutrient water (Rakocy, 1988). The styrofoam boards also shield the water from
direct sun light to help maintain lower water temperatures, which is beneficial for plant growth
(Rakocy, 1988). (re-word)

Lettuce and radishes were chosen because they are rapidly growing plants that can do
well in the reduced day length and cooler temperatures experienced in the fall in the Virginia
region. These plant types were readily available at Lynchburg Grows. The chosen media for this
experiment were soil, gravel, and coconut fiber, which were also provided by Lynchburg Grows.
All the media types were found on the Lynchburg Grows property, making it convenient to use
for the experiment. (Details about the media)
Once per week, the height of each lettuce and radish plant was measured in centimeters.
The heights were used to measure growth for each plant over time. Temperature, pH,
conductivity, and dissolved oxygen readings were taken at the at the inflow and outflow end of
the system. These parameters were used to access the water quality and make sure it was within
adequate range for the plants and the fish. Water samples were also taken at the inflow and
outflow end every week to measure nutrient levels available for the plants at entry and utilization
by the plants in the experiment.
The nutrients analyzed are phosphorus, nitrate and ammonia using standard protocols
developed for the Systea Scientific discrete auto-analyzer (Easy Chem Methology, 2009) (Put in
lit. cited). These nutrients were measured to ensure the adequate levels were available for
optimal plant growth.
All the plants from both systems were harvested on November 15, 2011. The NFT
heights were recorded for a total of eight weeks, while the floating raft plants were recorded for
five weeks. The plants in the floating raft had less weeks because the construction of the system
was not completed until mid October. All the plants had to harvested at the same time, regardless

of this time difference, because it was the getting near the end of the growing season and the
temperatures were beginning to get too cold. This experiment was only concerned with growth
over time in different media. The radishes and the lettuce plants were carefully removed from the
pots. Then the plant was cut were the roots met the stem. The foliage above the soil and the roots
below the soil were weighed separately to compare how much growth was dedicated to the roots
compared to the leaves.
Data Analysis
All the measurements for each plant in each media were averaged together were plotted
on a line graph to show growth of the plants over the course of the experiment. A single factor
ANOVA compared weights (total, above ground, below ground) of the plants grown in the three
media. Comparisons were made for each crop across the three different media within each
individual system. P-values were used to test significant difference in the mean plants weights
and, therefore, the overall growth among the three media.
Results
Radish Growth Rate in the Floating Raft
The heights if the radish heights for each media in the floating raft system were plotted
for each week (Figure 6). The graph shows a similar trend in growth rates of the radishes grown
in the gravel and soil. Radishes grown in fiber showed the least overall growth. The radish
plants grown in soil had the largest average end height (11.77cm), with gravel close behind
(11.19 cm), and fiber last in end height (3.075). (ADD STAND DEV)

height (cm)
14
12
10
8
6
4
2
Grav
el
Fiber
0
1 2 3 4 5
time (weeks)
Figure 6- Growth rates of radishes in floating raft system over the experimental time period in
each medium type. (fix fiber, gray scale-add color or different symbols, add points at each week,
error bars)
Radish Growth Rate in the NFT
The average radish heights in the NFT were plotted for each week for a total of 8 weeks
(Figure 7). In the NFT, soil showed the greatest growth. There was a continual growth for the
first 7 weeks and then a drop the final week. Radish growth in coconut fiber and gravel was not
as great as in soil. The radishes in the fiber had a negative growth and radishes in the gravel had
a spike in growth in the 3 rd week, but then a drop for the remainder of the experimental time.
(Did the plants shrink )

height (cm)
height (cm)
25
20
15
10
5
0
1 2 3 4 5 6 7 8
time (weeks)
Gravel
Fiber
Soil
Figure 7- Radishes grown in NFT system over the experimental time period in each medium
type.
Lettuce Growth Rate in the Floating Raft
Points were plotted on a line graph for the average height of lettuce plants in each
treatment in the floating raft for each week (Figure 8). Each media followed a similar growth
trend, however, soil had the greatest overall growth, followed by gravel, and then fiber. Lettuces
averaged 7.34 cm in height (STAND DEV) in the soil, 6.52 cm in height (STAND DEV) in the
gravel, and 5.7 cm in height (STAND DEV) in the fiber at the end of the experiment.
8
7
6
5
4
3
2
1
0
1 2 3 4 5
time (weeks)
Gravel
Fiber
Soil

height (cm)
Figure 8– Lettuce grown in Floating Raft system over the experimental time period in each
media type.
Lettuce Growth Rate in the NFT
The average heights for each week were plotted on a line graph to depict growth in each
medium (Figure 9). Soil was the most effective medium for lettuce in the NFT method as
assessed by average height over time. Lettuce grown in the soil showed much growth in the 8
weeks, with an average finished height of 18.12 cm. Lettuce grown in soil showed only a small
amount of growth over the 8 weeks. Plants grown in gravel showed only a small amount of
growth with only 1 cm of growth over the experiment. (STAND DEV)
20
18
16
14
12
10
8
6
4
2
0
1 2 3 4 5 6 7 8
time (weeks)
Gravel
Fiber
Soil
Figure 9- Lettuce grown in NFT system over the experimental time period in each media type.
Radish Weights in the Floating Raft System
To obtain the weights of the plants, a SCALE Was used. The majority of weight for the
radish plants came from the leaves/shoots (Table 1). Radishes grown in soils showed the greatest
average total weight, above ground weight, and below ground weight.

Table 1- Average biomass for radishes in Floating Raft (STAND DEV)
MEDIA TOTAL (g) SHOOTS (g) ROOTS (g)
GRAVEL 5.86 4.41 1.44
FIBER 0.60 0.38 0.22
SOIL 8.74 7.10 1.64
Radishes Weights in the NFT
There were no plants to weigh at the end of the experiment for radish plants grown in
gravel (Table 2). Almost all of the total weight for the radish plants grown in soil comes from the
shoot of the plant and the root represents a very small proportion of the total plant. The overall
biomass of radishes grown in fiber is much less than those grown in soil, but still most of the
weight comes from the shoot of the radish plant.
Table 2- Average biomass for radishes in the NFT
MEDIA TOTAL (g) SHOOTS (g) ROOTS (g)
GRAVEL 0 0 0
FIBER 0.09 0.07 0.01
SOIL 17.81 17.68 0.13
For total weights of radishes in the floating raft system there was a strong significant
difference in plants grown in soil compared to plants grown in fiber (Table 3). There was also a
strong significant difference when plants grown in fiber were compared to plants grown in

gravel. When the plants grown in gravel were compared to plants grown in soil, there was no
significant difference. For the shoot biomass, there was again a strong significance in plants
grown in soil compared to plants grown in fiber and plants grown in fiber compared to those
grown in gravel. There was no significant difference in plants grown in gravel and plants grown
in soil.
The results of the comparisons of root biomass between the three media showed there
was only a statistical significance between the plants grown in the fiber and the plants grown in
the gravel.
Table 3- Comparison showing P-values for radish plants in different media grown in the Floating
Raft and NFT.
Floating
Raft NFT
Total Biomass Gravel to Soil 0.15 0.07
Soil and Coconut Fiber

along with plants grown in gravel and plants grown in soil. Again there was no statistical
difference between radishes grown in fiber and radishes grown in gravel.
Lettuce Weights in the Floating Raft System
For all three treatments, the majority of the weight of the lettuce came from the shoots of
the plant (Table 4). The greatest total weight was seen in lettuce plants grown in soil, with
gravel close behind. Gravel as a media did not result in great overall growth for lettuce.
Table 4- Average weights for lettuce in the Floating Raft system
MEDIA TOTAL (g) SHOOTS (g) ROOTS (g)
GRAVEL 1.52 0.92 0.60
FIBER 0.84 0.59 0.24
SOIL 2.07 1.30 0.77
Lettuce Weights in the NFT
For all three treatments, a majority of the weight of the lettuce came from the shoots of
the plant (Table 5). Soil noticeably resulted in the greatest overall growth in both leaves and
roots, and thus total weight (14.38 g).
Table 5- Average weights for lettuce in the NFT
MEDIA TOTAL (g) SHOOTS (g) ROOTS (g)
GRAVEL 1.36 1.04 0.32
FIBER 0.07 0.04 0.03
SOIL 14.38 10.65 3.73

There was a significant difference between the total weights of lettuce grown in gravel
and lettuce grown in soil (Table 6). There was not a statistical significance in the comparisons of
the total weights of plants grown in soil and plants grown in fiber or plants grown in fiber and
plants grown in gravel. None of the comparisons of leaf or root weights were statistically
significant.
Table 6- P-values for lettuce plants grown in the Floating Raft and NFT
Floating
Raft
NFT
Total Weight Gravel to Soil 0.01 >0.001
Soil to Coconut Fiber 0.79 >0.001
Coconut Fiber to Gravel 0.15 0.04
Shoot Weight Gravel to Soil 0.36 >0.001
Soil to Coconut Fiber 0.17 >0.001
Coconut Fiber to Gravel 0.28 0.039
Root Weight Gravel to Soil 0.42 >0.001
Soil to Coconut Fiber 0.05 >0.001
Coconut Fiber to Gravel 0.08 0.07
For lettuce grown in the NFT, there was large significance in the total weights when
plants grown in gravel were compared to plants grown in soil (Table 6). There was a similar
result for the comparison between plants grown in soil and plants grown in coconut fiber. There
was a smaller significance between plants grown in coconut fiber and plants grown in gravel. For
the shoot weights, there was once again the large significance between lettuce grown in gravel
and lettuce grown in soil. There were similar results for the comparison between lettuce grown in
soil and lettuce grown in coconut fiber. Again, there was a significant difference between plants
grown in coconut fiber and plants grown in gravel. There was statistical significance in the root
weights between lettuce grown in gravel and lettuce grown in soil and between lettuce grown in

soil and lettuce grown in coconut fiber. No significant difference was found between plants
grown in coconut fiber and plants grown in gravel for any of the weights measured.
Nutrient Analysis
The nutrient analysis was not preformed on a consistent basis. However, the total
phosphorus levels decreased as the water flowed through the plant pots (Table 7). These water
samples were taken before the catfish were placed into the system. The nitrate and ammonia
levels do not show the same consistence with regards to the inflow and outflow. (NEED HELP
WITH NUTRIENTS)
Table 7- Nutrient concentration for the inflow and outflow of the NFT and Floating Raft
Total P
NFT
In
Out
9/23/11 0.051 0.039
9/27/11 0.067 0.06
10/3/11 0.09 0.073
Nitrate
NFT
FR
In Out In Out
11/4/11 0.007 0.01 0.061 0.063
11/11/11 0.127 0.068 0.0171 0.052
Ammonia
NFT
FR
In Out In Out
11/4/11 0.523 -0.047 0.702 0.713
11/11/11 0.024 0.011 0.515 0.534
Discussion
The medium in which a plant is cultivated plays a major role in it overall growth. A good
substrate in an aquaponic system maintains a nutrient reservoir in the root zone and provides
adequate air pore space for gas exchange (Sikawa, 2010). At the end of the experiment, both

lettuce and radish plants grown in soil showed the greatest growth in the NFT (Figures 7 and 9).
Lettuce performed well in the NFT because it requires consistent watering (Denckia, 2003).
Radishes need larger amounts of water than lettuce, which is still provided by the even and
constant flow of water in the NFT in soil. However, the water had to make contact with the seed.
The seed was planted in a tall pot and in order for the water to reach the seed. The media in the
pot needed to absorb the water so the water could reach the seed and allow for germination. The
soil was able to absorb enough water that it reached the seed. Soil has the ability to supply the
plants with enough water without becoming overly saturated. It does not hold on to water to
tightly where there is no air in the soil. Some of the spaces are filled with air, so there is an
aerobic environment, which is best for plant growth (McCauley et al., 2005).
Gravel did not perform well because it was unable to absorb the water need for the seed
to germinate. The gravel was too dry for the plant, therefore there was little overall growth for
both radish and lettuce plants in the NFT (Figures 7 and 9). The coconut fiber is very absorbent
of water, but this can cause over saturation reducing plant growth. In the NFT, both lettuce and
radish plants did show much growth during the experiment. The coconut fiber was able to absorb
the water and bring it to the seed at the top of the pot, but became too wet of an environment.
When the media becomes overly saturated, it causes poor aeration and anaerobic conditions for
the roots and reduces overall growth.
Soil once again preformed the best for both the lettuce and radish plants and resulted in
the greatest growth between the three medias (Figures 6 and 8). In the FR system, the roots grow
directly into the water so there is a constant supply of water and nutrients. Gravel plants in the
floating raft grew greater compared to in the NFT, maybe because the roots extended directly

into the water, providing the plant with a water supply without becoming overly saturated. The
part of the pot that was above the water line was able to drain allowing air to also reach the roots.
Fiber still did not perform well for the radishes because it was still over saturated for the plants
(Figure 6). The lettuce plants in the fiber showed better results, but still had the least growth
(Figure 8). The coconut fiber again became over saturated and it became anaerobic.
Soil is a viable media option to use in an aquaponic system because it is abundant and easily
purchased or even made by compose. Soil naturally contains nutrients that can be utilized by the
plants.
Plants grown in soil in both the NFT and floating raft showed considerable growth, but
when comparing both systems at the 5 week mark, the NFT had greater average growth up to
that point for both the lettuce and radishes. The height at 5 weeks for lettuce in NFT was 15.82
cm while it was only 7.34 cm in the floating raft. Radishes had an average height of 17.37 cm in
the NFT, and 11.77 cm in the floating raft. The NFT is the more a practical system to use to
grow the crops. There are already two structures at Lynchburg Grows that have large areas to
grow abundant amount of plants. If all the space is utilized, a large quality of plants can be
grown and eventually sold for profit.
The catfish were introduced to the system 4 weeks after the first set of plants were
planted. This means the fish provided no additional nutrients for the first month for the NFT, and
first week for the floating raft system. This could be an explanation for why plants grown in soil
performed the best. The soil already contained nutrients, so the plants used those nutrients for
growth. The total phosphorus levels were lower in the outflow because the media absorbed some

for plant use (Table 7). The data was not completed consistently enough to determine the effects
of the addition of the fish and just how much nutrients they added to the system.
The simplest approach to design an aquaponic system is to duplicate a standard system or
scale a standard system down or up. The UVI system has been well documented and is being
studied or used commercially in several locations, design for available space (Rakocy, 2006).
Several different plants can be grown in this type of agriculture method. Some plants
require more nutrients and require a larger density of fish to supply those nutrients. Lettuce,
herbs, and specialty greens (spinach, chives, basil, and watercress) have low to medium
nutritional requirements and are well adapted to aquaponic systems. Plants yielding fruit
(tomatoes, bell peppers, and cucumbers) have a higher nutritional demand and perform better in
a heavily stocked, well established aquaponic system (Diver, 2006).
There are some advantages to growing crops in an aquaponic system over growing in the
ground. Large reductions in chemical and water consumption have been achieved through the
use of an aquaponic system (Rakocy, 1989). The plants act as a bio-filter, so there is no need for
an separate bio-filtration system. Plus, this bio-filter produces income for the institute. There is
no need for addition chemicals and fertilizers because the fish provided the nutrients for the
plants. The fish waste would normally be discharged and would contribute to pollution. The
removal of nutrients by the plants prolongs the water use and minimizes total water
consumption. As an integrated system, it increases profit due to free nutrients, lower water
requirements, elimination of a separate bio-filter, less water quality monitoring, and crops and
fish can be produced in the same space and time (Rakocy et al., 2004).

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