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System Setup

Assembling a Vertical NFT System: Channels, Slope and Plumbing

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A step-by-step build order for a stacked NFT system — mounting uprights, setting slope on each tier, plumbing the feed riser and cascade returns, and pressure-testing before a single plant goes near it.

This lesson assumes a stacked vertical NFT system: several channels mounted one above another on uprights, a reservoir at the base, a pump feeding the top channel, and each channel draining into the one below before the lowest returns to the tank.

Bought a Hydro Works wall-mounted system? Skip this lesson for the build itself. Yours arrives fabricated — plant sites drilled, fittings fitted, and the channel fall already set by the bracket positions — so none of the cutting, drilling or levelling below applies to you. Follow Setting Up the Hydro Works Wall-Mounted NFT System instead. This lesson is here to explain why those things are built the way they are, and for anyone assembling a system from parts.

Work in this order. Each step is much harder to correct once the next is done.

Before you start

  • Lay out and count every part against the parts list. Finding a missing fitting halfway through plumbing is a wasted afternoon.
  • Dry-fit everything first. Assemble without glue or sealant, check it, then take it apart and do it properly.
  • Have these to hand: a spirit level (a 600 mm level is far better than a short one), a tape measure, a drill with masonry bits if wall-mounting, a pencil, PTFE tape, and a bucket.

Step 1 — Mount the uprights

The uprights carry the entire load, so they are the one component where care pays back most.

  1. Mark the upright positions, and check with a level that your marks are plumb — vertical. An upright leaning even slightly throws the slope of every channel it carries.
  2. Drill and fix into masonry wherever possible. If you must fix into plasterboard, locate the studs; plasterboard anchors alone are not adequate for a loaded system.
  3. For a freestanding frame, confirm the base is on level ground and will not rock. Shim it before going further.
  4. Check the uprights are square to each other and equally spaced before final tightening, or the channels will not sit parallel.

Step 2 — Set the channels and their slope

This is the step that determines whether the system works. Slope target is 1:30 to 1:40 (roughly 25 – 35 mm of fall per metre).

  1. Mount the lowest channel first and work upward — it is easier to reach past channels you have not fitted yet.
  2. Fit each channel with the outlet end lower than the inlet end. Confirm the direction before fixing; a channel mounted backwards is a common and infuriating error.
  3. Set the fall with a level. Rest the level along the channel: the bubble should sit just off centre, consistently, along the whole run. For a 1.2 m channel, 1:30 to 1:40 (roughly 25 – 35 mm of fall per metre) means roughly 30 – 40 mm of drop from inlet to outlet.
  4. Check for sag in the middle. A long channel supported only at its ends will bow, creating a puddle exactly where you least want one. Support the mid-span.
  5. Keep vertical spacing between tiers generous enough for the mature crop plus your hands. Lettuce wants 350 – 400 mm of clear height; tighter than that and you cannot harvest without damaging the tier above.

Test the slope with water, not just the level. Pour a litre down each channel and watch it. It should run steadily from end to end and leave no standing puddles. Any pooling is a low spot — fix it now.

Step 3 — Position the reservoir

Place the tank at the base, shaded, on level ground, and positioned so the lowest channel's return line drops into it with a clear fall. Check that:

  • The lid can still be opened with the system assembled — you will be doing this weekly.
  • You can get a hand to the pump to service it without dismantling the plumbing.
  • There is room to lift a full bucket over the tank when mixing.

Step 4 — Plumb the feed riser

The riser carries solution from the pump to the top channel.

  1. Sit the pump flat on the reservoir floor, or on a small stand if the tank collects sediment. Keep the inlet clear of the tank wall.
  2. Run the feed pipe up alongside an upright and clip it. An unsupported riser vibrates, works fittings loose and eventually leaks.
  3. Fit the flow control tap where you can reach it without a ladder. You will adjust it during commissioning and occasionally afterwards.
  4. Deliver into the top channel at its high end, discharging into the channel rather than onto a plant site. Aim the outlet along the channel, not across it.
  5. Use PTFE tape on threaded joints. Do not overtighten plastic fittings — they crack, and a cracked fitting on the riser drains your reservoir onto the floor.

Step 5 — Plumb the cascade and return

On a cascading system, each channel's outlet feeds the next channel's inlet, and the lowest channel returns to the tank.

  1. Make each drop as short and as steep as practical. Long shallow jumpers between tiers are where blockages start.
  2. Size the return generously. A return line narrower than the feed will back up eventually, and a backed-up channel floods its root mat. When in doubt, oversize the return.
  3. Avoid horizontal runs and sharp elbows in the return path. Every one is a place for root fragments and biofilm to catch.
  4. End the return above the maximum water line in the tank. A submerged return outlet can siphon the reservoir empty when the pump stops.

Step 6 — Fit net pots and light-proof the channels

  • Check every net pot sits with its base close to the channel floor. A pot sitting too high leaves the plug out of contact with the film, and the seedling never establishes.
  • Block every gap that lets light in. Light on the solution means algae. Algae means fouled pumps, depleted nutrients and crashed overnight oxygen. Unused pot holes should be plugged or covered.

Step 7 — Water test before nutrients

Do not skip this. Run the system on plain water for at least an hour before you mix a drop of nutrient.

  1. Fill the reservoir with plain water and start the pump.
  2. Walk the whole circuit and check every joint for weeping. Dry each joint with a cloth and look again after ten minutes.
  3. Confirm the film is running the full length of every channel — not just the top one. Adjust the tap until each channel carries a thin, continuous film.
  4. Confirm the return is keeping up and the reservoir level is stable.
  5. Now switch the pump off and watch. Confirm nothing siphons, nothing overflows, and the channels drain rather than holding standing water. This simulates a power cut, and it is much better to discover a siphon problem now than with a crop in the channels.
  6. Leave it running an hour. Check every joint one final time.

A system that passes the water test is ready to commission. Part 4 covers mixing the first nutrient charge and setting pH and EC.

Basic Hydroponics Training — the full series

  1. Part 1 — NFT Hydroponics Explained: How the Nutrient Film Technique Works
  2. Part 2 — Planning Your NFT System: Space, Water, Power and Crop Choice
  3. Part 3 — Assembling a Vertical NFT System: Channels, Slope and Plumbing (you are here)
  4. Part 4 — Commissioning Your NFT System: First Fill, Nutrients, pH and EC
  5. Part 5 — Planting Out: From Seed to Channel
  6. Part 6 — Weekly Maintenance and Troubleshooting for NFT Systems

Own our wall-mounted system? Setting Up the Hydro Works Wall-Mounted NFT System gives you the build and commissioning steps for that specific unit.

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