DWC Grow Canals:
Canals can be of variable lengths, from one to
tens of meters, enabling an adequate nutrient
supply due to the large volume of water
used in this system. As far as the width is
concerned, it is generally recommended to be
the standard width of a sheet of polystyrene,
but it can be multiples of this. However,
narrower and longer canals enable a higher
water speed that can beneficially hit the roots
with larger flows of nutrients. The choice of
width should also consider accessibility by the
operator. The recommended depth is 30 cm
to allow for adequate plant root space and to
allow for sufficient water flow.
Like fish tanks, canals can be made from any
strong inert material that can hold water. For
small–scale units, popular materials include
fabricated IBC plastic containers or fiberglass.
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Much larger canals can be constructed using
wood lengths or concrete blocks lined with
food–grade waterproof sheeting. If using
concrete, make sure it is sealed with non–
toxic, waterproof sealer to avoid potential
toxic minerals leaching from the concrete into
the system water.
The retention time for each canal in a unit
is 1–4 hours, regardless of the actual canal
size. This allows for adequate replenishment
of nutrients in each canal. Plant growth will
benefit from faster flow rates and turbulent
water because roots can then be exposed by
many more ions, whereas slower flows and
almost stagnant water would have a negative
impact on plant growth.
Aeration for DWC units is vital. In a densely
planted canal, the oxygen demand by the
plants can cause dissolved oxygen (DO)
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