Article: by Brynn Simpson
Photos supplied
T
wo Dam Sustainable is
a small trout farm operated by Marco and Vivian Harms on Langhoogte Farm, up a dead end valley outside of Montagu. Two things make
Two Dam Sustainable remarkable
(besides the quality of their smoked
trout products, obviously!). Firstly
part of their production comes
from a Recirculating Aquaculture
System (RAS) and secondly they
operate off the power grid.
The recirculating aquaculture system, built by Deep Blue Aqua, is a
moderately complex aquaculture
system whereby water is reused
many times over prior to being sent
to waste. Solids are removed and
bio-filtration is used to convert toxic ammonia produced by the fish to
non-toxic nitrates that are removed
through water replacement. Alt-
hough there is a continuous flow of
new water into the system, it is designed to operate with a low replacement rate (daily replacement
of 15% of the total tank volume).
In an area like Montagu where water is scarce in summer, that’s important.
Water is plentiful and cold in winter
but summer presents a more stressful situation for Marco and all his
trout as water flow volumes in the
nearby river fall dramatically and
temperatures start to rise, exceeding 25oC. Marco’s challenge has
been controlling the heat in the
system. Cooling was an imperative,
but without the option of using
energy hungry equipment. A combination of evaporative cooling systems and new water fed from a
deep borehole has allowed Marco
to continue production right
through summer.
Being “powerless” has presented a
host of challenges to the Two Dam
Sustainable team. The farm has no
Eskom or Municipal power connection, leaving alternative energy as
the only possible sustainable source
of power. Marco has made use of
solar panels and a water turbine to
provide power for the trout farm
and has installed an LP gas generator as an emergency back-up.
Marco’s smoked trout is gaining
quite a reputation in the local area
and beyond. Two Dam Sustainable
supplies trout to a number of local
restaurants and is often seen at local markets on the weekend.
You can get hold of Two Dam Sustainable at [email protected] and Deep Blue
Aqua at www.deepblueaqua.net.