How it works

A little more detail for those who are interested

If you want the short version

A stepper drives a toothed belt, which drives a carriage along a linear rail, which carries your pump. The interesting part isn't the motion. It's the housing.

The contamination problem, both ways

Put a linear bearing above a reef tank and two things happen. Wear debris — polymer dust, metal particulate, degraded lubricant — falls downward into your water. And salt aerosol rises upward into your bearing. Most designs solve one and lose to the other.

Fusion Flow uses a channel-section inner track: a floor beneath the rail with an upstand either side. Debris falls into it and is retained; the floor runs the full length, so nothing reaches the water. An outer cover encapsulates that channel from above and descends past it on both sides, leaving a pair of downward-facing clearance apertures for the carriage to pass through.

Because the cover's lower edge sits outboard of and below the channel's, there is no straight path in. Splash has to rise into a downward-facing aperture, turn inward past the descending skirt, then climb over the upstand before it can touch the rail.

Debris travels outward and down, and is caught. Aerosol travels inward and up, and is stopped. One geometry, two opposed problems.

The carriage is deliberately flexible

A powerhead on an arm applies a fluctuating moment to the bearing every time the flow gusts. Left unchecked, that pounding brinells the recirculating elements and the carriage eventually binds.

So the carriage is compliant by design — it deflects a fraction of a millimetre under peak load and returns without permanent set, acting as a damper between your pump and the bearing. The rail is then sized so the damped load sits at roughly half the bearing's permissible static moment, leaving margin for reversals, gusts and the occasional knock during maintenance.

Setting it up takes about a minute

There's no app and no PC. Power it up and it finds its own datum. Then you can enter teach mode and physically push the carriage to where you want the sweep to start, and again to where you want it to end. It remembers both.


One button, one speed dial, one status LED. Tap to pause while you feed or work on the tank, and it picks the sweep back up on its own after ten minutes. Taught positions are stored in flash, so after a power cut it re-homes and resumes the same sweep without being asked.

Built so a pump is never left parked

A stationary powerhead blasts one spot continuously, and sensitive corals don't survive that treatment for long. So the firmware is built around a single hard rule: keep moving. A control fault degrades to continued motion rather than stopping, and a pause you've forgotten about times out and resumes automatically. That constraint shaped the whole control design.



Materials

  • Housing

    PETG. Chemically inert, dimensionally stable, no additives of concern in an aquatic setting. Reinforced with stainless steel in applicable areas.

    Explicitly not: photopolymer resin. Incompletely cured photoinitiators can leach into water, and that's not a risk worth taking above a reef.

  • Carriage bearing

    Stainless Steel

  • Rail

    Hardened steel, greased, and enclosed. Any ball-bearing linear guide needs a hardened raceway, and hardened steels — stainless included — trade corrosion resistance for that hardness. So the rail is protected by the housing rather than by its alloy.

  • In service

    The prototype has run continuously above a marine tank since January, and the rail shows no corrosion. That's one unit in one tank — a first data point, not a service life. I'll publish more as units accumulate hours.



  • Pump mount, magnet route

    Your pump's own magnet in a carrier — 40, 60 or 75 mm. Nothing clamps to the pump body.

  • Pump mount, mechanical route

    Friction-fit cradle, currently for the Jecod/Jebao SOW range. No magnet enters the tank.

Is it noisy?


It isn't silent, but no, it's certainly not noisy.

There's a mild hum at full speed, but no whine — the motor runs in a quiet stepping mode — the carriage travelling on its bearing makes a soft mechanical sound, and the cover carries some of that along the length of the sweep.

At its slowest speed, however, it is truly "silent"

The audio clip is measured with the tank running and the microphone 5cm from the cover. From a normal sitting/observation distance (1 m+), there is no noticeable acoustic output, using my tank as an example.

(Be careful with the volume levels if you have to turn your device up; remember to turn it back down!)

It really is pretty quiet. 😊

Specifications

The range

Sizes
Four, named by their sweep — 230, 330, 430 and 470
Sweep
230 / 330 / 430 / 470 mm of travel
Over tank
310 / 410 / 510 / 550 mm — this is what has to clear the tank opening
Overall length
385 / 485 / 585 / 625 mm — the whole unit, including the speed dial and heatsink standing proud of the end
Suits tanks
340–440 / 440–540 / 540–580 / 580 mm and over, front to back inside the glass
Finish
Black or white, same price, chosen at checkout
Price
£229 / £279 / £339 / £399

Where four figures are given they run in size order: 230 · 330 · 430 · 470.

Motion

Principle
Carries your existing powerhead along a rail above the tank, so the origin of the flow moves instead of the flow being aimed from one fixed point
Sweep length
Set by you, anywhere up to the full travel
Sweep speed
5.4 to 35.6 mm/s, set on the dial
Time end to end
Fastest, about 6 / 9 / 12 / 13 seconds. Slowest, about 42 / 61 / 79 / 87 seconds
Two units
Run independently of one another. Nothing synchronises them
Arm extension
230 to 280 mm
Discharge angle
Set on a clevis, and stays where you put it

Those times are one traverse. A there-and-back cycle takes twice as long — about 13 seconds on a 230 at full speed, up to just under three minutes on a 470 at its slowest.

Control

Controls
One button, one speed dial, one status LED
Connectivity
None. No app, no wi-fi, no account, no firmware server to be discontinued
Pause
Tap the button to hold the carriage still for feeding or maintenance. It resumes on its own after ten minutes, with the indicator switching to a fast blink for the last thirty seconds, so a powerhead is never left parked
Setting the sweep
Taught by hand — enter teach mode, push the carriage to each end, done
Position sensing
Closed-loop feedback. The controller knows where the carriage actually is, not just where it was told to go
After a power cut
Limits are held in non-volatile memory. It re-homes itself and resumes the sweep you taught it
Fault behaviour
A control fault degrades to continued motion rather than stopping the carriage. A parked powerhead damages corals, so nothing in the firmware — and nothing the user can press — is allowed to park it indefinitely
Drive
Quiet stepping mode across the whole speed range

Pump mounting

Magnet mount
Uses the magnet your pump already came with. Carriers for 40, 60 and 75 mm magnets, any manufacturer. The 60 mm is the one supplied as standard
Mechanical mount
Friction-fit cradle, nothing magnetic in the water. Currently for the Jecod/Jebao SOW range
Tested with
Jecod/Jebao SOW-4, SOW-8 and SOW-15 · D-D Funktion 10
Maximum pump thrust
10 N — SOW-15 class
Maximum pump weight
500 g
Pump body
Nothing clamps to it on the magnet route

Construction

Housing
PETG throughout — chemically inert, no additives of concern above a marine tank
Not used
Photopolymer resin, anywhere in the product
Finish
Printed to order, so fine layer lines are visible close up and there is slight variation between units. Checked for stringing, warping and blemishes, and for dimensional accuracy on rail alignment, clamp fit and the sealing geometry
Carriage
Stainless
Rail
Hardened steel, greased and enclosed. Every recirculating-ball guide needs a hardened raceway, and hardened steels trade corrosion resistance for that hardness — so the rail is protected by the housing rather than by its alloy
Debris channel
Runs beneath the rail, catching wear debris and retaining it. Nothing reaches the water
Cover
Overlapping, leaving no straight path from the tank to the rail. Splash has to rise into a downward-facing aperture, turn inward past the skirt, then climb the channel upstand
Drip edge
Returns condensation to the tank instead of letting it run inward
Compliant carriage
Deflects under peak load and returns, damping the pump's fluctuating moment before it reaches the bearing
Protection
This arrangement is the subject of UK patent application GB2619546.1

Power and dimensions

Supply
12 V DC from an external supply. No mains voltage anywhere in the unit
Included
UK three-pin power supply
Consumption
4 W maximum
Unit weight
1,400 to 1,800 g depending on size
Above the rim
77 mm
Behind the back glass
65 mm — drive end, heatsink and speed dial. The part measures less; the figure published is the one to plan around
Out over the water
310–550 mm depending on model

The 65 mm matters if the tank is pushed tight to a wall. Measure that gap before you order.

Installation

Fixing
Clamps to the rim. No drilling, no adhesive, no cabinet modification
Tank types
Rimmed and rimless
Time to first sweep
About 15 minutes from the box
In the water
Nothing except the arm and the pump mount
Pump cable
Carried in a loose hanging loop that reshapes as the carriage travels, spreading the movement along its length rather than working one spot. As fitted, the tightest radius is about 50 mm — ten times a typical 5 mm powerhead cable, which is the accepted minimum for a cable that flexes continuously. Two anchor points at the drive end and two on the carriage, one each side, so the loop can be kept open whichever side your pump’s cable leaves from
Setting the cable slack
Carriage to the drive end, where the loop hangs deepest — check it stays clear of the water. Carriage to the far end — check the cable is not pulling tight. Anywhere between the two is right. If your cable is thicker than about 5 mm, allow a little more slack: the figure to beat is its own diameter times ten

Maintenance

Each water change
About a minute — wipe the housing, check the clamp, listen to one sweep
Every four weeks
About 15 minutes — cover off, clear the debris channel, wipe and re-grease the rail, check belt tension
Every six months
About 30 minutes — the above on a bench, plus belt, cable and mount magnets
Bearing
A replaceable service part. Interval depends on your pump — annually for an SOW-15, three-yearly for an SOW-8
Grease
NSF H1 food-grade synthetic. A tube comes with the unit

In the box

Unit
Assembled and tested
Pump mount
60 mm magnet carrier as standard. If you need the 40 mm, the 75 mm or the mechanical cradle instead, say so with your order and it is supplied in place of the 60 mm at no extra cost
Power
12 V supply, UK plug
Grease
Tube of NSF H1
Documentation
Printed setup and maintenance card

Compliance and protection

Patent
Patent Pending — GB2619546.1, filed August 2026
Registered designs
UK 6548662–6548668, registered August 2026. Cover how it looks — the complete apparatus, housing, support arm, telescopic arm, clamp and pump mount, each registered separately
Conformity
UKCA declaration of conformity covering electromagnetic compatibility and RoHS
Origin
Designed, built and tested in the UK

Buying it

Change of mind
14 days from the day it arrives, no reason needed, under the Consumer Contracts Regulations 2013
Warranty
12 months
Lead time
4 weeks
Production
Built in small batches by one person. If a batch slips you get told before the date, not after

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An automatic discount applies to two units of the same size at checkout.

Built to order — up to 4 weeks. Free UK delivery by Royal Mail Special Delivery — signed for and insured.

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