nutrient application systems
“ CENTRIFUGAL PUMPS will either pump a small volume of water to a high delivery head or a large volume of water to a low head .”
PUMPS
Most NFT hydroponic systems utilize centrifugal pumps , which can produce a constant flow of nutrient solution rather than the pulsating flow associated with piston or diaphragm pumps . Centrifugal pumps will either pump a small volume of water to a high delivery head or a large volume of water to a low head . A delivery head is the highest point that the pump must push water to in a system . With NFT systems , the delivery head is the height measured from the surface of the nutrient solution in the reservoir to the top of the growing channels . To select the correct size of pump that will deliver the correct volume of nutrient solution , you need to determine the system ’ s delivery head height , flow rate in liters or gallons per minute , and — for basic NFT systems — the number of channels . ( The standard rate of a basic NFT system is one liter per minute per channel .) These specifications can be listed on pump packaging either as a pump performance curve showing head capacity at different flow rates , or simply as flow rate at a set head height . Also , growers should be aware that pump capacity and flow rates tend to fall over time , and with increasing nutrient temperature . Allowing for future system expansion is always a good idea .
DRIP IRRIGATION
As mentioned above , drip irrigated hydroponics is the most commonly used method of nutrient application . These may be set up and run as either a batch feed or inline dosing system . Smaller indoor gardens often utilize batch feeding , in which a central tank containing several days ’ worth of working-strength nutrient solution is made up and manually adjusted for EC and pH . This solution is irrigated onto the plants using a pump and timer or manually controlled by the grower as required . Batch feeding is easy to set up and run ; however , time is required to mix up the working-strength solution every few days . Inline dosing is a more automated system widely used in commercial hydroponic operations . Also known as ‘ fertigation ’ or ‘ direct dilutor / injector systems ’, inline dosing systems are installed on the main water supply . As water flows through , nutrient concentrates and pH control chemicals are directly dosed into the flow at the correct rate to obtain the EC and pH required for a crop . Inline injector systems may use several different designs for
Adjustable flow emitter allows nutrient solution volume to be controlled separately for each plant .
Ebb and flow nutrient application used on a seedling nursery bench system .
NFT flow rates down each channel need to be uniform and at the correct volume .
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