Plants consume oxygen via the roots for the
process of ‘respiration’.
Oxygen also aids in keeping the nutrient sterile by satisfying the oxygen
demand of aerobic processes.
For these 2 processes to occur, the oxygen must
be dissolved in the nutrient solution. This is achieved via ‘aeration’.
Simply exposing a body of water to air does not
achieve adequate aeration.
System design generally determines how much
oxygen dissolves in the nutrient solution. Maximum aeration is achieved by
breaking the water up into small droplets via tumbling (e.g. waterfall) or
spraying (e.g. fountain). In
systems, aeration can be achieved by:
- Delivering the nutrient solution via spray
- Designing the hardware (for recirculating
systems only) so that the nutrient splashes into the reservoir when it
returns from the roots.
In either case though, good ventilation must be
provided for the space where the aeration occurs. Failure to achieve this
will cause the air in that space to become depleted of oxygen -
- An air stone and air pump can also be used.
Air stones have the added advantage of promoting circulation of the nutrient
solution to ensure uniformity (Fig 9.3). Make sure to locate the pump in a
well ventilated area.