Because the water on the "wet" bulb temperature sensor evaporates, water from the reservoir must be continuously fed to the sensor. This is achieved using a wick which draws up water, relying on the principle of capillary action.
Stringent demands are placed upon this wick. If the wick does not provide enough water or it dries out, the climate computer will calculate a too high RH and then, incorrectly, take measures to eliminate this apparent high humidity by venting or possibly even by increasing the temperature. Apart from the fact that this is a considerable waste of energy, in reality, a RH develops which is too low, potentially even resulting in crop damage.
Therefore it is essential to have a wick that will continue working reliably for many weeks at a time.
The wick may dry out due to deterioration of its capillary capabilities. This can be caused by impurities in the measuring unit, such as lime scale, particles that are sucked in by the fan, e.g. airborne dirt, dust and especially insects, but also by the growth of algae in the reservoir. In addition, micro-organisms (bacteria and fungi) can also develop in the water and in the wick.
Note that tap water creates limescale and therefore should never be used in the unit.
However, by using Aquanex Measuring Unit Fluid instead of demineralised water, the reservoir is 'automatically' kept clean. The fluid opposes the growth of algae, fungi and bacteria. Impurities that enter the reservoir are broken down.
Aquanex Measuring Unit Fluid keeps the capillaries in the wick open by expanding them very slowly. This prevents non soluble dust particles from blocking the transport of the fluid.
Aquanex has been on the market since 1992 and has been thoroughly tested. Using precision instruments, the Centre for Agrotechnology and Physics (TFDL) has determined that Aquanex does not affect the calculated humidity value.
"Measuring humidity is vitally important to growing a quality product, and that's where Aquanex comes in."
- Wim Grootscholten (see references)