AI Axis 20/40/90 — DC Centrifugal Return Pump Anti Back-Siphon Mobius - AquaIllumination

The AI Axis pumps are submersible DC-motor return pumps, available in three sizes. AquaIllumination bills them as "big pump features in pumps of all sizes": full control, wireless smart device programming, quiet DC motor operation, and output calibration — features that have traditionally been reserved for considerably larger and more expensive pumps.

The driver is integrated into the pump, and the body is smaller than a soda can.

Back-Siphon Prevention — the Feature Nobody Explains

Here's the classic return pump problem. When it shuts off — to feed, for maintenance, for a power cut — water in your display siphons back down the return line and empties into the sump. Two consequences: your sump can overflow, and on restart the pump pushes the accumulated air column into the tank as bubbles.

AquaIllumination's solution is elegant. The manufacturer puts it this way: with calibration set, instead of powering off, the pump will continue to run without producing flow. It holds the water column in place instead of letting it drain back. No siphon, no overflow, no bubbles on restart.

That's the "big pump feature" in the slogan: something you'd normally only find on industrial-grade pumps.

The 3 Modes

• Schedule: create a custom program with changing flow over time
• Feed: temporarily reduces flow to prevent food from being cycled into the overflow
• Calibrate: calibrate your pump to your aquarium — set min and max flow levels

Another useful detail: according to AquaIllumination, the control button on a single pump turns all your AI pumps on or off at once. One press before feeding, and the whole system goes into Feed mode.

Picking a Size — and the Max Head Trap

The advertised flow rate isn't what you'll get. A return pump loses flow as it lifts water: that's Max Head, the highest it can push. At its maximum height, flow drops to zero.

Measure the vertical distance from your sump water level to where the water enters the display, then leave yourself margin. An Axis 20 that has to climb 4 feet won't give you 185 GPH.

Nozzles Included — Two per Pump

Every Axis ships with two barbed output nozzles in different diameters. Check that one of them matches your plumbing before ordering:

• Axis 20: 0.5in. (12mm) and 0.625in. (16mm)
• Axis 40: 0.625in. (16mm) and 0.75in. (20mm)
• Axis 90: 0.75in. (20mm) and 1in. (25mm)

Control

• Mobius: free iOS and Android app
• myAI: also compatible
• Neptune Apex: through Apex Fusion with the MXM module

It's the same app as your Prime fixtures and Nero pumps — all your AI gear in one interface.

Technical Specifications

Axis 20

• Width: 2.125in. (54mm) · Height: 5.5in. (139.7mm)
• Input: 100–240VAC, 50-60Hz, 1A

Axis 40

• Width: 2.44in. (62mm) · Height: 6.625in. (168.2mm)
• Input: 100–240VAC, 50-60Hz, 1A

Axis 90

• Width: 2.91in. (74mm) · Height: 7.75in. (196.85mm)
• Input: 100–240VAC, 50-60Hz, 1A

All three are submersible DC-motor pumps with an integrated driver.

What's in the Box

• 1 x AI Axis Pump with Integrated Driver
• 2 x Barbed output nozzles (two diameters)
• 1 x Power Adapter with Universal Plug Adapter Set
• 1 x Quick Start Guide

Why Choose ReefSolution

Authorized AquaIllumination dealer in Canada with technical support in French. Choosing a return pump comes down to head height, not just flow — give us the distance between your sump and your display and we'll tell you which model to take. Shipping across Canada.

Complementary products:

• AI Orbit 2 — in-tank cross-flow: the Axis handles return, the Orbit spins the water
• AI Nero 5 — the directional powerhead, same Mobius app
• AI Nero 3 — the compact directional, for nanos and AIOs like the Axis 20
• AI Orbit 4 — high-power cross-flow, to pair with an Axis 90 on a big system

Frequently Asked Questions

Which Axis pump size should I choose for my reef tank?

AquaIllumination recommends the Axis 20 for tanks up to 15 gallons (AIO and nano), the Axis 40 up to 40 gallons, and the Axis 90 up to 90 gallons. But check Max Head too: 5 ft. for the Axis 20, 9 ft. for the Axis 40, 10 ft. for the Axis 90. If your sump sits well below your display, height decides, not volume.

How does the Axis prevent back-siphon?

According to AquaIllumination, with calibration set the pump doesn't power off: it keeps running without producing flow. That stops water from draining back down the return line, which avoids both a sump overflow and air bubbles on restart. It's a feature usually reserved for far more expensive pumps.

What's the difference between an Axis and a Nero?

Two completely different jobs. The Axis is a centrifugal return pump: it lives in your sump and lifts water back to the display. The Nero is a powerhead: it lives in the tank and moves water around. A reef system with a sump needs both.

Does the Axis pump need to be fully submerged?

Yes. The Axis pumps are submersible — they run underwater in your sump's return chamber. Factor in the model's height to make sure your water level covers it: 5.5in. for the Axis 20, 6.625in. for the Axis 40, 7.75in. for the Axis 90.

What output nozzle comes with the Axis?

Two barbed nozzles are included with every pump. Axis 20: 0.5in. (12mm) and 0.625in. (16mm). Axis 40: 0.625in. (16mm) and 0.75in. (20mm). Axis 90: 0.75in. (20mm) and 1in. (25mm). Check that one of them matches your return plumbing.