Hydroponic NFT Tunnel Greenhouse 6m Wide 25m Long Galvanized Frame Complete

A hydroponic tunnel only pays for itself when the water side is designed together with the frame. Buyers who bolt NFT channels into a house that was never planned for them end up with uneven slope, air locks in the return line and a pump that runs dry. This 6 m x 25 m house is laid out from the channel back: 1.5 percent fall over 22 m of growing run, a 1,000 litre buffer tank on a level plinth outside the crop area, and a frame with 1.2 m arch spacing that carries both the roof load and the hanging weight of four rows of channels. The structure is hot dip galvanized at 275 g/m2 and the film is 180 micron UV stabilised with anti drip.

• NFT channel layout included: Four rows of 100 x 50 mm food grade PVC channels, 22 m run, sloped at 1.5 percent, with a 1,000 litre tank and a 0.75 kW pump sized for 6 m3/h.
• Dutch bucket and grow table ready: Same frame accepts 12 Dutch buckets per row or two 1.2 m rolling benches, so you can change system without changing the house.
• 180 micron anti drip film: UV stabilised outer ply, anti condensation inner face, 90 percent transmission, 30 percent diffusion to reduce tip burn on lettuce.
• Hot dip galvanized structure: 275 g/m2, 1.2 m arch spacing, designed for a hanging load of 25 kg per metre of purlin in addition to roof loads.
• Drainage and irrigation routing: Gutter outlets at both ends, a 110 mm perimeter drain, and pre drilled cable ports for EC and pH probes.
• Food grade wetted parts: Channel, tank and fittings in PVC and HDPE, no recycled material in contact with nutrient solution.

Three numbers decide whether an NFT tunnel works: run length, slope and flow rate. A 22 m run at 1.5 percent needs a 330 mm height difference from inlet to outlet, and if the channel is not supported every 1.2 m it sags between hangers and creates a low spot where roots sit in standing water. We supply the channel with a pre punched hanger slot at 1.0 m, and the frame purlin sits at the exact height so the fall is built in rather than shimmed on site. Flow is set at 2 litres per minute per channel, which on four rows of 22 m comes to roughly 6 m3/h for the whole house and a tank turnover every ten minutes. That is the figure the pump is chosen against, not the tank volume.

Lettuce and herbs want 12 to 16 mol/m2/day, so a 6 m house in a bright site with 90 percent transmission is enough without supplemental lighting for most of the year in southern Europe, Mexico and Southeast Asia. The risk is humidity, not light. Anti drip film moves condensation to the gutter, roll up sides give cross flow, and we recommend running a 20 percent side opening even in cool weather to keep the canopy dry. If you are growing in a tropical site, ask for the 40 mesh net on both sides; the airflow penalty is small and the thrips control is worth more than the light you lose.

A hydroponic house carries weight that a soil tunnel never sees: channels full of water, plants, and in some layouts a pipe grid. This frame is rated for 25 kg per metre of purlin in addition to 0.40 kN/m2 wind and 0.25 kN/m2 snow, with 1.2 m arch spacing and a 2.0 mm wall. Hangers are stainless steel wire with a safety factor of 5, and the purlin is a 40 x 40 mm tube rather than the thin C section found on cheap kits. If you plan to add a second tier of channels later, tell us at the quotation stage: the spacing changes and it is much cheaper to build in than to retrofit.

Fill and circulate for 24 hours before planting to check for air locks, then measure the fall with a laser level at three points along each channel. Electrical work should go to a licensed electrician; the pump circuit needs a residual current device and a dry run cut out, because losing a crop to a burnt pump is an avoidable cost. In daily operation, check EC and pH at the tank every morning, top up with fresh solution rather than raw water, and flush the lines every three weeks. The house is designed so all of this can be done from the aisle without stepping into a channel row.

Typical buyers are lettuce and herb growers in Malaysia, Indonesia, Thailand and the Philippines working 500 to 3,000 m2, restaurants and hotels in the Gulf running a 6 x 25 m house for year round greens, and EU growers in the Netherlands, Poland and Ireland using it for propagation before field planting. The complete set, including channels, tank and pump, loads into a 40HQ at about 31 cubic metres with the frame nested inside the channel crate.

Channels are crated with end caps fitted, the tank ships with a lid and bulkhead fittings already installed, and the pump travels in its own foam lined carton. Frame bundles are numbered to the layout drawing. Checks include channel wall thickness, a 2 bar pressure test on the tank outlet, pump flow test at 6 m3/h, zinc weight on the arches, and a dry assembly of one bay with hangers. The frame is warranted 10 years, film 3 years and the pump 2 years; spare clips, hangers and fittings ship with every order, and our technician can review your layout drawing before production at no charge.