CREATING AN ECOSYSTEM
At a fundamental level, aquaponics is the combination
of aquaculture (the cultivation of fish) and hydroponics
(the cultivation of plants without soil).
Normally in an aquarium setup without live plants,
heavy filtration and water changes are required to
prevent the accumulation of fish waste from harming
the fish. Too much excrement can quickly spike the
levels of ammonia in the aquarium, sickening or
killing fish.
In a well-balanced ecosystem, nitrifying bacteria break
down this ammonia into nitrites, and then nitrates —
forms of nitrogen that is useful to plants. Fish eat and
create waste; bacteria break down that waste into
their own waste; and plants feed on bacterial
byproducts to grow.
plants absorb nutrients to grow
clean water is
returned to the tank
waste water is
pumped out
of the tank
aste
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fish pr
KEEPING IT ALL IN BALANCE
The aquaponics project at PJP focuses on a specific
type of plant — the kind humans can harvest and
consume as food. Brussel sprouts, spinach, corn, and
lettuce are just some of the vegetables grown by 12th
grader Brian Williamsen. “The most difficult part is maintaining the pH of
the water,” Cottman agreed. While baking soda was
previously being added as needed to the tank to reach a
neutral pH, the teacher shared that one of his students is
working on a more precise solution to the problem:
“Getting the fish acclimated and getting
the plants growing isn’t easy,” Williamsen
told Ignite. “Fish require a lot of care and
need the perfect conditions.” As someone
with experience growing and harvesting
vegetables, Williamsen knew how important
the details are to caring for plants, and was
quickly learning how those same lessons
apply to raising fish. “[He] is learning how to calculate the amount of baking
soda needed through stoichiometry and acid-base
reactions,” Cottman said. By combining science, math,
and an understanding of ecological balance, Cottman’s
classmates are learning what it takes to keep the system
going — and growing.
Classmate Mark Mellensky shared Williamsen’s thoughts
on the importance of ecosystem balance.
“You have to be patient,” Mellensky said. Prior to this
project, he had never raised fish before, but was excited
to test his skills in the aquaponics lab. “The water pH
level has to be just right; keeping it at the right level can
be hard to balance!”
fig.1 trout
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