Tower Sourcing in the USA: Pot and Center Pipe

The tower is designed around European parts: a 38 × 38 × 40 cm square planter and a 20 mm OD center pipe. Neither is easy to find in the US. This page collects what builders in the MakerWorld comments (about 1,200 ratings; read through 2026-11-12) actually used, plus my own sizing checks. Claims are marked (commenter) where a builder reported them, and (calc) where I worked them out from standard sizes. Nothing here has been built or tested by me yet.

Center pipe (20 mm OD)

The pipe carries water up the middle and, per the designer, also adds stability. It runs through a 20 mm bore in every module, so anything that sticks out past the OD will not pass: no welds, rivets, or external couplers.

What commenters used

Standard US sizes against the 20 mm bore (calc)

So 3/4" OD tube is the closest US match. A metric 20 mm tube from a supplier such as McMaster-Carr is another route, but I have not checked stock.

The aluminum tubes I am considering

Two 3/4" OD, 6 ft candidates. The Everbilt tube is the better fit: its thinner wall leaves a 16.6 mm ID, about 70% more flow area than the Grainger tube’s 12.7 mm ID (calc), and it is close to the roughly 17 mm ID of a 20 × 1.5 mm tube.

Everbilt 3/4 in x 6 ft aluminum round tube (archive): specs from a screenshot of the listing (retail page, in stock for store pickup on 2026-11-12). Measure the real OD with calipers; the thinner wall is more flexible, so handle it carefully.

Grainger 6061 aluminum round tube, item 795AP1 (archive):

Spec as shown on the listing; check the current page before ordering.

• Length: a single 6 ft piece means no joint. The designer’s 180 cm tower includes the pot and the pipe stops 1 cm above the Rainbase, so 183 cm should just do it. Add up your module heights first; a taller build will not fit.
• OD: 0.95 mm under the bore. Take up the slack at the pump connector with PTFE tape or heat shrink, or print a connector with a 19.05 mm bore. A loose connector is where leaks start (the designer’s fix for leaks there is a sealing ring).
• ID: the Grainger tube’s 12.7 mm gives roughly 45% less flow area than a 20 × 1.5 mm tube (about 17 mm ID; the designer’s wall thickness is not stated) (calc); the Everbilt’s 16.6 mm is nearly the same as that tube. It matters because the pump has to lift water about 1.8 m. Check the pump’s maximum head against the finished tower height before relying on it; I have not verified the Syncra’s head rating.

If you have to join shorter lengths

Use an internal sleeve: a tube that slides inside both ends, 4 to 6 in long, scuffed, degreased, and bonded with two-part epoxy, with the sections butted tight. Welding thin aluminum tube needs TIG and leaves a bead that must be ground flush. Rivets and screws leave heads that snag in the modules. With the Everbilt tube (16.6 mm ID) a 5/8" OD (15.9 mm) sleeve leaves about 0.7 mm of clearance for epoxy. The Grainger tube’s 12.7 mm ID is too small for that, so with it just buy the 6 ft length.

Epoxy and food safety

Cured epoxy is generally inert, but look for NSF/ANSI 61 (drinking-water components) or FDA 21 CFR 175.300 compliance on the datasheet for the exact product. Avoid metal-filled putties. Wipe out squeeze-out so no bead is exposed to flowing water, mix at the stated ratio, cure fully (often 24 h or more), and flush the system with plain water before planting. An epoxy-free alternative is a tight press-fit sleeve sealed with 100% silicone sold as aquarium-safe (bathroom silicone often contains mildewcide).

Aluminum in nutrient solution

One commenter worried aluminum reacts with fertilizer salts at pH 5 to 6.5 and suggested PVC-U or polyethylene. The designer found no evidence against aluminum online and is in their third season with it. Someone else planned a polyethylene pipe (cheap, easy to cut, 10 m coil). If it bothers you, choose stainless or plastic.

Ring uprights (optional support structure)

The “Rings V4” print profile needs four 1 m uprights of 16 mm OD pipe. In the US, 1/2" PEX works (15.9 mm). One builder put a 7/16" wooden dowel inside the PEX to stiffen it. Copper also fits but is expensive. In Europe the part is sold as “rigid M16 installation pipe”.

Pump

Commenters used the Sicce Syncra Silent 2.0 (designer’s pick), a 700 GPH “WUCIOOO” pump, and a 40 W, 3000 L/h pump. The pump I plan to use:

VIVOSUN 660GPH submersible pump, size 6"×4"-660 (archive), from a screenshot of the listing on 2026-11-12:

• Lift margin: the tower needs about 1.8 m of lift, 72% of the pump’s max head, so about 0.7 m of margin at shutoff (calc). Actual flow at 1.8 m will be well below 660 GPH, and the pipe’s friction takes more. Test it half full as the designer advises and use the flow adjuster if it sprays too hard.
• Outlet adapters: three threaded barbs come in the box, 0.5", 0.62" and 0.75". None fits inside the 16.6 mm ID pipe, because barb ridges are wider than the nominal size. Use the 0.75" barb with a 2 to 3 in piece of 3/4" ID flexible tube, clamped on the barb, with the pipe pushed into the other end. The tube’s OD (about 1 in) does not matter because the joint sits below the lid. Do not clamp the pipe end: the pipe has to slide out for cleaning. The flexible tube also forgives a pump that is slightly off-center, but the outlet should still be near dead center under the pipe. Use the 0.62" or 0.5" barbs only to throttle flow; their bore sizes are not stated.
• Cord: it has a molded plug. Check it fits through the lid’s square cable hole before assembly.

Pot (reservoir)

The designer’s requirements: at least 40 L (10 gal), square, thick upper rim, no drain holes, plastic (polyethylene preferred), drillable rim. The footprint is about 38 × 38 cm.

Avoid:

• 5-gallon buckets. The designer says that is too small for a tower this size, and one builder who adapted a thin square pot said the sides bulged when it filled.
• Galvanized steel cans. Suggested once in the thread; they would rust in nutrient solution.
• Thin-walled planters. One builder found a planter weak where the tower mounts.

Reservoir size matters. One builder says a 40+ L pot lasts about 4 days in summer if filled to the top; another lost track of pH and had to change the water repeatedly.

Build and print gotchas from the comments

• Weak tabs. The joiner tabs on the main body break during printing or later (several builders). Printing with the BigTower with connector supports profile helps. Updated V5 profile moves the seam to the middle and slows the speed.
• Feet failing on GrowSmall4 and Grow8. The bottom right foot fails on some printers (P2S reports). Changing the seam to random fixed one; adding hand-placed supports fixed another.
• Wet PETG. Dry PETG first, even new rolls. Several builders say that fixed their failures.
• Print bed. The rings do not fit on a 220 × 220 mm bed (K1C); the rest does.
• Filter flap leaks. Too thick a foam pad caused it for one builder (thinner pad fixed it). Others used sealing tape, or a U-shaped TPU gasket (a flat 0.6 mm gasket made it worse). A “no flap” base option exists in the print profiles.
• Missing a Big4 pot. The Grow8 pot with four top connectors has no offset, so with one fewer Big4 pot the rings will not attach (one builder hit this at 2 m tall).
• Nuts stuck. An M5 nut jammed and blocked disassembly; embedded or heat-set nuts are suggested.
• Layer leaks. Silicone or a seal at each seam if you mount the base to a board (see the four-tower build above).
• Top rain module arms failed repeatedly for one P1S owner; the designer asks about brims and infill (use grid, crosshatch or gyroid, not something sparse).

Growing notes from the comments

• A builder grew 72 strawberries in one tower; high flow also kept water temperature stable in heat.
• Another runs EC at 1800 to 2200 for fruiting crops. Lettuce and herbs need much lower.
• Rockwool starts, with clay pebbles in the net pot, per the designer. Clay can skew EC and pH readings, and one builder asked for printed inserts instead.
• Several people added lights: LEDs built into the support rings, or a taller lid. Files are on other MakerWorld pages (one linked at the designer’s invitation).
• PETG is fine in water, and white PETG reflects sun but encourages algae; the top parts are black for that reason.
• Existing commercial towers: one builder scaled the model to 86% so their mesh pots and clips fit.

Shopping check before you buy

• Pot is square, 10+ gal, no drain holes, drillable rim, or you have a board to adapt it
• Pump max head is above tower height plus the extra loss from a narrower pipe
• Center pipe OD is within about 1 mm under 20 mm and has a way to seal at the pump
• Pump connector matches the pipe OD (printed connector in the print profiles)
• Epoxy, if used, has an NSF 61 or FDA 21 CFR 175.300 datasheet
• PETG is dry before printing

Open questions

• Real flow of the VIVOSUN 660 at 1.8 m lift through the 16.6 mm ID Everbilt pipe (or 12.7 mm ID Grainger), and whether the lift is enough to reach the sprinkler.
• Whether the 3/4" ID tube grips the 19.05 mm pipe snugly enough to seal without a clamp; pot depth minus pump height sets the pipe length and the joint length, so dry fit first.
• Whether the VIVOSUN plug fits the lid’s cable hole.
• Alloy of the Everbilt tube (not stated on the listing).
• Whether the printed pump connector can be re-sized for a 19.05 mm pipe, or whether tape is enough.
• Which US pot to use. The 27-gal tote and a plywood adapter is the most reported without custom CAD.