Prep Tools

Auto-Siphon

A pump-primed racking cane that starts a siphon with one stroke to transfer brew off its sediment.

An auto-siphon is a rigid racking cane inside a slightly larger tube that, with a single pump, primes and starts a gravity siphon. Brewers and winemakers use it to transfer fermented liquid into a new vessel while leaving the settled yeast and sediment behind. The pump action avoids mouth-priming, keeping the transfer sanitary and reducing oxygen pickup.

The Auto-Siphon is a racking cane with a built-in piston pump — one of those quiet, purpose-built tools that reshaped home brewing and winemaking once it became standard kit. Instead of sucking on tubing to start a siphon or rigging up a separate hand pump, the user works the plunger a few times and gravity does the rest. Mechanically, it is a rigid length of food-grade plastic tubing with a hand-operated piston inside the upper cylinder, a check valve at the bottom outlet, and a threaded cap that seals against a fermenter bucket or carboy neck.

The tool solves the two persistent annoyances of racking: getting flow started without contamination or splashing, and stopping the transfer before the lees get pulled over. A single firm stroke of the plunger evacuates air from the tube and pulls liquid up over the bend; once primed, gravity sustains the flow on its own. The fixed bottom cap holds the outlet a set distance above the trub bed, so the transfer naturally winds down before sediment is disturbed. In that sense the device behaves less like a pump and more like a self-priming valve with a built-in sediment buffer.

After priming, the plunger is essentially out of the equation. Everything that follows is governed by the height difference between the fermenter and the receiving vessel, which is why aggressive pumping is counterproductive: it whips oxygen and foam into the liquid rather than speeding transfer. A brewer or vintner who understands that the device is gravity-driven once primed treats it as a precision instrument, not a pump.

Alternatives

Plain Racking Cane With Mouth StartGravity Transfer HoseSmall Transfer Pump

Types & varieties

Standard Auto-Siphon (3/8 in.)

The original size. Slower flow and the least splashing of the lineup — preferred for finished beer where oxidation is the enemy.

Auto-Siphon 1/2 in.

Larger bore moves liquid faster and has the head height to keep long vertical transfers going. Best for wine with heavy lees or any thick, particulate-laden liquid; trades speed for more turbulence.

Big Mouth Auto-Siphon

Fitted with a wide-mouth cap sized for specific wide-mouth fermenters and buckets. Same internal pump and check valve, just a different sealing collar.

How It Works

The device is simpler than it looks once you see it as three pieces: the threaded cap, the pump cylinder, and the inner tube with bottom cap. The cap threads onto the fermenter and creates the airtight seal the siphon depends on. The pump cylinder houses a piston attached to the plunger handle on top, and the bottom of the inner tube is fitted with a one-way check valve (the foot valve) that lets liquid enter from the fermenter but not return.

To start the flow, the user works the plunger: pushing it down closes the foot valve and forces the air (or liquid) inside the cylinder out through the outlet; pulling it back up opens the foot valve and creates suction that draws fresh liquid from the fermenter up into the tube. After a stroke or two, liquid reaches the top of the inner tube and spills over the bend, where gravity carries it down into the receiving vessel.

From that point on, the plunger is essentially decorative. The check valve holds the column of liquid in place, and gravity does the work as long as the receiving vessel sits below the source. Flow rate is controlled by elevation: lower the receiving vessel to speed the transfer up, raise it to slow the flow down. The bottom cap is sized so its outlet sits a fraction of an inch above the deepest point of the fermenter, leaving the trub bed undisturbed at the end of the run.

The cap creates the airtight seal — without it the pump cannot establish a prime.

Choosing the Right Size

The 3/8-inch model is the default for beer. Its narrow bore minimizes splashing and the oxygen pickup that comes with it, which matters most in pale, hop-forward styles where any oxidation shows up fast. The 1/2-inch version is the better choice when the liquid is heavy, the lees are deep, or the vertical run is long — wine transfers, mead pulled off a thick yeast cake, and tall carboys all benefit from the extra bore and head height. The Big Mouth variant is simply the right pick when the fermenter in use has a wide-mouth opening rather than a standard carboy neck.

Care and Cleaning

The Auto-Siphon is one of the easier tools to keep sanitary because it comes apart by hand — no tools required. The plunger, cylinder, tube, and bottom cap all separate for cleaning, and hop debris, wine tannins, and dried yeast are the usual culprits when it misbehaves. A soak in a no-rinse sanitizer before each use is standard practice; after use, rinsing immediately while residue is still wet prevents the check valve from fouling, which is the single most common cause of a siphon that won't hold prime.

Common uses

Racking finished beer from a fermenter into a bottling bucket or directly into a kegTransferring wine off heavy lees after primary or secondary fermentationPulling cider or mead clear of sediment for bottling without disturbing the cakeMoving liquid between carboys when stepping up or racking off a secondaryDraining sanitizer or cleaning solution from a fermenter after scrubbingSplitting a batch between two vessels during secondary conditioning

Tips & pitfalls

Sanitize every part — pump, tube, and bottom cap — with a no-rinse sanitizer before each use; contamination almost always traces back to a missed component.
Keep the bottom check valve submerged the entire time; lifting it out of the liquid breaks the prime and the siphon dies mid-transfer.
A single firm stroke is enough to start the flow. Hard, repeated pumping only oxidizes the batch and creates foam.
Never use on carbonated beverages. Dissolved CO2 comes out of solution as the pressure drops and the vessel will foam over.
Use gravity to control flow rate, not the pump — start with the receiving vessel low and raise it later to slow the flow.
Twist the cap snug onto the bucket or carboy before pumping; an air leak at the seal will prevent the siphon from priming.
Rinse and disassemble immediately after use. Dried hop residue or wine tannins will foul the check valve and cause it to leak on the next run.
For very tall carboys, the 1/2-inch model provides enough head height to keep flow going; a 3/8-inch can stall partway through a long vertical run.
If the siphon refuses to start, the check valve is almost always the problem — pop the bottom cap off, rinse the valve and seat, and reassemble.

Good to know

Primary use: Transferring fermented beer, wine, cider, or mead off sediment during racking
Manufacturer: Fermtech (now part of Northern Brewer)
Standard inner diameters: 3/8 in. and 1/2 in.
Materials: Food-grade polypropylene body with silicone or plastic seals
Source of suction: Integral piston pump — no mouth-priming, no separate pump
After priming: Gravity maintains flow; the pump is not in continuous use
Cleaning: Disassembles by hand; sanitize with a no-rinse sanitizer such as StarSan
Common alternatives: Plain racking cane, mouth-primed gravity siphon with tubing