NFT Fixed Bench Systems
NFT Fixed Bench Systems are a popular choice for commercial hydroponic growers.
They can be operated by one grower and everything is fixed in position for the lifetime of the system. This makes it very easy for one or more staff members to plant, harvest and clean the system.
An NFT Fixed Bench System is especially suitable for growers who wish to grow a wide variety of plants, which mature at different ages.
In a typical Fixed Bench NFT system you can grow approximately 11 plants per square metre of greenhouse area.
If used exclusively for lettuces; Based on a 450 gram mature lettuce size and 8 crops of lettuce per year this system could yield 88 plants per square metre of greenhouse area per year (including pathways) or 39.6kg of lettuces per square metre per year. (yields will vary depending on climate and lettuce variety).
If the farmer prefer to grow smaller lettuces and sell them “per head” rather than “by weight” then they can easily push out more crops per year for a higher return.
The Fixed Bench systems are most popular for Lettuces, Herbs, Leafy Greens, Chinese Vegetables and Strawberries.
- The NFT Fixed benches typically use 100x50mm gully and are most usually 8 gullies wide (1.6m wide) x 6 metres or 12 metres long.
- A bench which is 8 gullies wide means that the centre of the bench is easily accessible from both sides during planting or harvesting.
- The fixed benches typically have a minimum 850mm wide pathway around all four corners of the bench. This allows easy access at all times and enables trolleys and other equipment to be used around the benches without any restrictions.
- Support frames are normally placed at 1.5 metres – 1.65 metres apart to support the gully from beneath. Failure to provide adequate support frames can result in sagging of the gully between the supports when the gullies are fully planted. This can result in ponding or a deeper flow of nutrient solution inside the gully resulting in root stress.
- PVC Saddles are placed over the gullies on every second support frame to lock the gullies in place on the top of the bench. This prevents any movement during storms or when the gullies are bumped during planting or harvesting. (Some gully designs have a small lip on the base to allow a screw to be inserted to fix the gully in place).
- At one end of the NFT Fixed Bench is the Feedpipe system which pumps a thin film of nutrient solution into the top of each gully. The feed pipe system has an adjustable control valve to allow a 1 litre per minute flow rate to be maintained down each 100x50mm gully. (Wider, shorter or longer gullies require a slightly different flow rate).
- Two 4mm I.D feeder microtubes per gully are used so that if one blocks the other can still function. A rubber top hat grommet holds the microtubes in place on each gully.
- At the opposite end of the bench a catchment system is installed. This is usually a light proof gutter with 8 slots to allow the tips of each gully to be inserted. As the nutrient solution flows out of the gullies and into the catchment system it is diverted into a common area where it falls into a vertical return pipe and down into a gently sloping return pipe. The return pipe collects all the return solution from nearby benches and directs it back to the mixing tank in the pump room.
- A sanitation system in the pump room (e.g. Oxine or Ozone) targets any pathogens which may be introduced into the mixing tank.
- A minimum 1:40 slope is maintained down each gully to enable a thin film of nutrient solution to be maintained and to prevent any ponding.
- Growers can steer the crops to be more vegetative or generative or to have hard or soft foliage by adjusting the nutrient strength (EC) of the nutrient solution.
Pure Hydroponics can design and supply full Fixed Bench systems to fit an existing greenhouse or we can supply a turn-key system comprising of an NFT Fixed bench system, greenhouse and climate control.
For growers located in distant countries we also offer a shopping list and design service which allows growers to source PVC pipework and common equipment locally and Pure Hydroponics supplies the specialist equipment only such as NFT gullies, dosing control system and NFT system accessories. This keeps freight costs down for the grower and can make the overall project more affordable.
Please contact Pure Hydroponics for a per m2 estimate for an NFT Fixed Bench system or a quotation for shopping list and design services.
All interested parties must complete the attached Commercial Design Questionnaire as part of their enquiry.