Mechanical filtration is not an effective tool to prevent water borne diseases in NFT hydroponic nutrient solutions. It has been found that the total organic carbon content can reach 20 mg.L-1 for 2-3 months without affecting plant growth. There are many other compounds that attribute to the total carbon mass such as chelates and the [...]
The correct flow rate of closed hydroponic systems is critical for optimal growth of plants. The flow rates are important for all types of closed hydroponic systems such as pure NFT systems, gravel cultures and ebb-and-flow systems. Inadequate flow rate will result in: Reduced oxygen levels at root surfacesIncreased susceptibility of diseasePlants are under stress [...]
LDPE HDPE Difference is crucial when designing a good system. You can either save a lot of money initially and waste a lot later when your irrigation system starts popping. The irrigation pipes ensure that water is supplied to the plants. The most common used pipes are the LDPE types. They range between 1 and [...]
Installing a sump on small closed hydroponic systems is also easy. The same basic concrete sump can be build but a simple ‘T-piece’ as described in the figure below can also be as effective. However, floating particles in the water will not be removed with this method. The water in the ‘inline sump’ must not [...]
A basic layout of a dripper irrigation system is provided using bags. Note the position of the filters in relation to the pump and water supply. Solenoid valves can be installed but the position will depend on the size of the block or number of plants that need to be irrigated at a time. The [...]
There are two basic types of dripper systems used in bag culture; 1 mm spaghetti pipes and 8 mm pressure regulated dripper (also called a PC dripper) which is much more expensive. There are advantages and disadvantages of both these types. The 1 mm spaghetti pipe is very cheap and easy to install. If blockages [...]
Bag culture systems requires the use of large tanks to store the nutrient mixture. The tanks are important because: The nutrients are mixed and stored in the tanksThe exact amount of nutrients can be added to a specific volume of water since the size of the tank is known.The exact amount of water can be [...]
The basis on which to choose a small nutrient tank or large nutrient tank will be: The relative volume circulating at any given time in the whole systemThe rate at which the solution formulation must be changedThe estimated risk that diseases can enter the system and how effectively it can be controlledCapital availableAmount of water [...]
Hydroponic nutrient tanks can be made from any type of material as long as it does not react or cause a reaction with the nutrient solution. For instance, galvanized tanks are not suitable if the nutrient solutions come in direct contact with the metal. If galvanized tanks are used, the plants will show a Zn [...]
Efficiently design dripper irrigation systems will ensure long term durability with minimum maintenance. The ideal requirements for efficient operation of dripper systems are: The delivery must be uniform and drippers must not stop easily (Capillary tubes or PC-drippers give the best results)Installing drip limiters such as PC-drippers that limit flow between 1.0L.h-1 to 4.0L.h-1 provide [...]
Plastic gullies (or also called hydro-liners) are made from thick durable plastic with a thickness between 125 micron and 500 micron. The recommended thickness to use is the 500 micron plastic. Although it is much more expensive, it is also more durable especially during the building phase where people tend to walk over the plastic [...]
Blocked drippers is a cause of frustration. It happens all the time and is something all growers must be wary of. Blockages occur due to physical matter in the water, black algae or salt build-up at the tip of the dripper system. There is no cure for blockages. The main cause for blockages can be [...]
Over the years, closed hydroponic systems have been criticized quite often for their high initial capital cost and the perception that these systems have a high disease risk. During the initial development of the closed system in 1961, these criticisms might have been true since little scientific knowledge was available. Since 1961 an enormous amount [...]
