configurations

by

absorbing


the


nutrients


from

the


water


and

from

there


the


water


is


returned


to


the


fish

tank;
Depending

on

the


sophistication

and

cost


of


the


Aquaponics


system,


the


units

for


solids

removal,


bio

-

filtration,
and/or

the


hydroponics


subsystem

may


all


be

combined


into

one

unit


or


subsystem,

which

prevents


the


water
from
flowing

directly

from

the


aquaculture


part


of


the


system

to


the


hydroponics


part.
Reservoir
A
reservoir


is


nothing


more


than


a

container

that


can

hold


water


positioned

between


the


grow

beds

and

the
fish
tank.



Some

systems

need


a

reservoir


to


help


keep

the


water


level

in


the


fish

tank


at


optimum


height.



In
order

to


take


it

a

step


further,


you

could


install

a

float


valve


in


the


reservoir


that


would

allow


water


from

a

water
source

(hose/PVC


water


pipe)


to


automatically


add

water


to


the


reservoir


when


evaporation


has

made


it
necessary.
Nitrification
Although

selected


minerals


such

as

iron

are


sometimes


added,

the


main

source


of


nutrients


for


the


plants

is
the

fish

waste.


Ammonia


is


steadily


released


into

the


water


through


the


excrement


and

gills


of


fish

as

a
product

of


their


metabolism.


Higher


concentrations


of


ammonia

(commonly


between


500

and

1,000


ppm)


can
kill

fish,


and

plants

do

not


absorb

it

as

well


as

nitrates.

This


means


that


nitrification,

or


the


aerobic


conversion
of

toxic

ammonia

into

nitrates,

is


one

of


the


most


important


functions


in


Aquaponics


since


it

reduces

the
toxicity
of


the


water


and

makes


it

easier


for


the


plants

to


take


up

the


nitrogenous


compounds.
Necessary

bacteria
Maintaining
a

healthy


population

of


Nitrosomonas

bacteria

that


converts


ammonia

into

nitrites,
and
Nitrobacter


bacteria

that


converts


nitrites


into

nitrates


is


the


most


important


element

in


an

Aquaponics
system.

These


bacteria

reduce

the


toxicity

of


the


water


resulting


in


compounds

that


can

be

used

by

the


plants
for

nourishment.


This


process


occurs


throughout


the


system,


as

the


bacteria

responsible

for


this

process


will
form
a

bio

-

film

on

all


solid

surfaces


of


the


system

in


contact


with


the


water.


Submerged

roots


of


the


plants

in
the

system

have

a

large


surface


area


which

also


contributes


to


living


space

for


said


bacteria.
Bio
-

filtration

assistance
Most

aquaponics

systems

include

a

bio

-

filtering


unit


which

helps


facilitate

growth


of


these


microorganisms.
Typically,

ammonia

levels

range

from

0.25


to


2.0


ppm;


nitrite


levels

range

from

0.25


to


1

ppm,


and

nitrate
levels
range

from

2

to


150

ppm.


During


a

system

start

-

up,


spikes


may


occur


in


the


levels

of


ammonia

(up


to
6.0

ppm)


and

nitrite


(up


to


15

ppm),

with


nitrate


levels

peaking


later


in


the


start

-

up

phase.


Since


the
nitrification

process


acidifies

the


water,


non-

sodium

bases

such

as

potassium

hydroxide


or


calcium


hydroxide
can
be

added


for


neutralizing

the


water's


pH


if

insufficient


quantities


are


naturally


present


in


the


water


to
provide

a

buffer

against


acidification.
Aquaculture

subsystem
Freshwater

fish

are


the


most


common


aquatic


animal


raised


aquaponic

systems

although


crayfish


and

prawns
may

also


be

used.


In


practice


in


America,


Tilapia


are


the


most


popular


fish

chosen


for


home


and

commercial
projects

that


are


intended


to


raise

edible

fish,


however


in


Australia


Barramundi,


Murray

cod

etc.


are


also


used.