Design and Control Systems for Hydroponics: Part Two-Growingequipment update

摘要

In the last issue of GE, we recapped some of the important aspects of setting up a good hydroponic growing system. Once we have understood the growing environment requirements, we can then take a look at the design and control of the hydroponic system. After all these years I still occasionally find a system that has no automatic method of water makeup. Systems without auto water makeup are a recipe for disaster! Even small hobby systems should be provided with a reliable method of replacing the water being used by the plants. The problem that results if you do not make such provision is that the plants often just use the water and do not remove any significant quantities of nutrient. This situation regularly occurs during times of high transpiration. The result of this is that the conductivity is now rising and sometimes at an alarming rate. Soon the conductivity becomes so high that now transpiration is reduced to dangerous levels and reverse osmosis can now occur. Fortunately for many growers, plants such as tomatoes are very resilient and will suffer such abuse many times before finally dying. The reduction in yield, however, cannot be disputed! Plants such as lettuce will not forgive such treatment.