The return pump is the heart of a marine aquarium. It ensures proper skimmer operation, consumes minimal energy, and provides the required flow rate. Today, we have the Octo VarioS 2 in our hands, our next return pump. Let’s dive into our review.

The Octo VarioS 2 may not be the first choice that comes to mind for your marine aquarium’s return pump. However, we were intrigued by one key detail: its exceptionally low power consumption. This led us to choose it as our return pump, and before putting it into operation, we tested every aspect—consumption, flow rate, and head pressure.

In short, we found no weak points. Not only do its performance metrics match Octo’s claims, but we also discovered outstanding maintenance ease and record-low power consumption. We’ve never seen a pump with this level of efficiency. And the noise? Although we didn’t measure it, it is virtually inaudible. Keep reading to see all the data we recorded in our review.

The pump operates at 24V and is adjustable in five steps, making it suitable for a wide range of marine aquariums. We appreciated its color scheme but were less enthusiastic about the gray connectors—we would have preferred red to match the base and rear casing. The pump comes with two sets of hose adapters in different diameters. A crucial note: never use the smaller adapter! Read why in our article on saving energy in marine aquariums.

The Octo VarioS 2 is a centrifugal pump with an alternating current motor that operates at a low, adjustable voltage. As always, we measured head pressure, flow rate, and power consumption. For head pressure, we used our standard static method. For flow rate, we used the DigiFlow 6710M flow meter, and for power consumption, we relied on the RCE PM600.

Video Review of the Octo VarioS 2 Return Pump

Before diving into the technical data, check out our in-depth video review. We not only discuss the pump and its performance but also explain head pressure and the differences between technical and measured values. We provide guidance on sizing and demonstrate our testing procedures. It’s a must-watch! Use English subtitles if you need it.

Octo Varios 2 Technical Specifications

The Octo VarioS 2 boasts an impressive energy efficiency of 120 liters per watt and an economic efficiency of 11.5 liters per second per euro (though we’ll soon explain why the high price isn’t an issue). With a reference value of 6,000 l*m/h, this pump is suitable for most Italian aquariums.

At a premium price point, you’re investing in a solid, reliable pump that operates at low voltage, is adjustable across 5 steps, and comes with excellent baseline features. It also includes a float switch to automatically shut off the pump if the sump water level drops too low. While its energy efficiency is outstanding, its economic efficiency is lower—though this is negligible when you consider the long-term savings on energy consumption. Let’s dive into the lab results and see how it stacks up against other pumps we’ve tested.

Construction

The pump features a simple, cylindrical design. The cap screws on and off by hand, making maintenance a breeze. In just a few seconds, you can open and close the pump without tools or worrying about screws corroding over time. Check out the video to see how quick and easy it is.

Inside the box, you’ll find the pump, two pairs of rubber mounts (of different diameters), and two PVC fittings for rigid piping setups. Important note: Never use the smaller rubber mount.

The impeller is modern, with 5 curved blades, which sets it apart from older pumps with similar flow rates. This design significantly improves efficiency.

Controlling the Octo VarioS 2

The pump’s flow rate and head pressure can be adjusted across 5 power steps. Using the integrated controller, you can set the flow rate and head pressure by increasing or decreasing the motor speed (remember, it’s a 24V motor). Additionally, there’s a button to pause the pump for 15 minutes (e.g., for feeding) or 60 minutes (e.g., during water changes)—a feature many overlook but one that’s incredibly convenient. The controller displays the settings via 5 blue LEDs, indicating modes from ECO to Normal and up to MAX.

The FS button activates the float switch, and the display shows its status.

The pump connects to the controller and power supply via a pair of connectors. Below, you can see the series of LEDs that light up as you switch between ECO and MAX modes.

For all our measurements, head over to page 2.

Head Pressure Test

Our first test measured the pump’s head pressure—its ability to lift water to a certain height. We measured the water level inside a rubber hose.

As shown in the archived photo, we secured the hose to a terrace, turned on the pump, and waited 10 minutes for stabilization before taking measurements. We repeated this process for each power step. You can see a snippet of this methodology in the video. Here’s the table of results.

Head pressure ranges from 220 cm to 385 cm, with a linear increase across all power steps. The maximum declared head pressure is 400 cm, so our measurements are nearly identical, accounting for minor reading errors. Great job, Octo! The water level in the hose remains perfectly stable—a behavior we don’t always see.

Flow Rate Test

Measuring the flow rate was straightforward using the DigiSavant DIGIFLOW 6710M flow meter. We connected the pump to the meter and ensured a tight fit. The flow rate is displayed in liters per minute, which we converted to liters per hour by multiplying by 60.

Here are the results:

The maximum flow rate was 2.766 l/h (46.1 l/min × 60), slightly below the declared 3.000 l/h. This means the pump achieved 92.2% of its declared flow rate under test conditions—an excellent result and one of the best we’ve measured for a variable-flow centrifugal pump. For comparison:

• Ecotech Marine Vectra M1: 66%
• Waveline DC6000: 67%
• Hydor Seltz D6000: 70%
• Rossmont RX 3200: 86%
• ASF NewJet NJ2000: 82.3%
• Amtra Stream Sump 4000: 92.3%

Pro tip: To maximize flow rate, always use the largest rubber mount, the widest tubing, and minimize the length and number of 90° bends in your setup.

Energy Consumption Test

We measured energy consumption using the RCE PM600, which also calculates the power factor (Cosφ). Results are displayed in watts.

The maximum declared consumption is 25 watts, while our measurements showed 25.9 watts—a mere 3.6% difference. At this consumption level and an energy cost of €0.27/kWh, running the pump continuously at max power would cost about €61/year or €5/month—a negligible expense.

Due to the pump’s size and flow rate, we couldn’t perform our usual noise test. However, the video demonstrates its near-silent operation. The included 4 soft rubber feet further reduce vibrations and noise.

Final Thoughts

The Octo VarioS 2 exceeded our expectations. It delivers on its promises, particularly in flow rate, where many pumps fall short. All measured values align closely with the manufacturer’s claims—a rare achievement.

Comparison with Other Pumps

We compared the Octo VarioS 2 with pumps from Amtra, ASF, Eheim, Hydor, Tunze, Sicce, Corallinea, Waveline, and Ecotech Marine. Here’s a summary:

The Octo VarioS 2 is not the most economical in terms of flow rate per euro, but its low energy consumption makes it a cost-effective choice in the long run. Its technical efficiency is unmatched, setting a new record at 107 l/h per watt.

Conclusion

The Octo VarioS 2 is a top-tier return pump with a reference value of 5,325 l*m/h (vs. the declared 6,000 l*m/h). Its 12% deviation is excellent compared to competitors, many of which perform far worse. If you’re looking for a reliable, efficient, and quiet pump, the Octo VarioS 2 is hard to beat.

PROS

Record-low energy consumption
Excellent performance, matching declared values
Solid build quality
Nearly silent operation
5-step adjustability
Easy maintenance

CONS

High upfront cost (though easily offset over time)

Disclaimer: We thank Octo for providing the VarioS 2 pump for this review.

Let’s Discuss!

If you have questions, doubts, or need help choosing the right return pump, leave a comment below.