If your pool still operates with a single-speed pump, you're likely overpaying for filtration that isn't even the most efficient. ESPA's NOXPLUS solves both problems at once: it consumes less, filters better, and operates almost silently.

 

NOXPLUS 1 HP — single-stage centrifugal pump with variable speed, available in 220V

What is the NOXPLUS?

The NOXPLUS is a single-stage, variable-speed centrifugal pump specifically designed for the recirculation and filtration of small and medium-sized pools. Unlike a traditional pump that only has one operating mode (either 100% on or off), the NOXPLUS adjusts its rotation speed according to the work cycle the pool needs at any given moment: startup, pressurization, extended filtration, or surface skimming.

This ability to vary the speed—instead of always running the motor at full throttle—is why it saves energy, makes less noise, and filters water better, all at the same time.

• Energy savings of up to 70%
• Longer equipment lifespan
• Ultra-quiet operation
• Easy handling, automatic configuration
• Improved filtration and water quality
• Self-priming up to 4 m

Real automation: 3 speeds that work on their own

One of the design successes of the NOXPLUS is that it doesn't require the user to manually adjust speeds. When turned on, the unit performs an automatic sequence designed for each stage of the filtration cycle:

• 5 minutes at high speed — to quickly prime the pump and pressurize the entire installation.
• Medium speed — efficiently maintains system pressure during normal filtration.
• High speed on demand — activates when greater flow is needed, for example, for surface skimming.

The result is a pump that "knows" when to exert more force and when to slow down, without the owner having to think about it.

Savings, in real numbers

The clearest comparison is against an equivalent single-speed pump (such as the Silen S 1 HP line). Both can filter the same volume of water, but electricity consumption changes dramatically:

In other words: the NOXPLUS achieves the same filtration result by extending the operating time but significantly reducing the power consumed per hour, which translates into energy savings of up to 70% compared to a traditional single-speed pump.

Performance curve

The operating curve shows how the NOXPLUS performs at each of its speeds, relating the manometric head (H, in meters) to the flow rate (Q, in m³/h). The three operating curves—low, medium, and high—are clearly visible, as well as the difference between the 115V and 230V versions at high speed:

NOXPLUS operating curves

At low speed, the pump delivers up to 180 l/min with a maximum head close to 3.5 m — ideal for continuous low-consumption filtration work. At high speed (230V), it can reach up to 15.5 m of head and flow rates of 350 l/min, perfectly covering peak demands such as priming or skimming.

Note: in Costa Rica, only the 230V version is distributed.

What pool volume is it suitable for?

A simple technical criterion for estimating this is the recirculation time: how many hours the pump needs to pass the entire volume of the pool through the filter at least once. In residential pools, a complete recirculation every 6 to 8 hours is usually sought if operating at high or medium speed, or in longer cycles (12 to 20 hours) if low speed is used to save energy.

Taking the already cataloged flow rate of the NOXPLUS at low speed (8 m³/h)—the regime in which it operates most of the time—the recommended pool volume according to daily filtration hours would be:

In practice, this positions the 1 HP NOXPLUS as the ideal choice for small and medium-sized residential pools, from approximately 30 to 90 m³ (e.g., rectangular pools from 6×3×2 m up to 10×5×1.6 m), leaving room to use medium and high speeds during peak demand moments—priming, pressurization, or surface skimming—without overloading the equipment.

Cleaner water filtering at lower speed

Here is one of the most counterintuitive—and most valuable—facts about variable speed technology: filtering slower does not mean filtering worse. On the contrary, it improves the final water quality.

When water passes more slowly through the filter medium, it remains in contact with it for longer, giving the filter the opportunity to retain a larger proportion of particles with each pass. A pump at maximum speed moves more liters per hour, but each particle has "less time" of exposure to the filter before returning to the pool—that's why more flow does not mean better filtration.

Particles present in water according to filtration speed — NOXPLUS technical presentation, ESPA

The graph confirms this with concrete data: to reach the same level of cleanliness (10% of remaining particles in the water), the pump operating at low speed (20 Hz) achieves it in just 2.2 recirculation times, while at medium speed (40 Hz) it takes 3.9, and at high speed (60 Hz) up to 4.5.

In other words: the same pool becomes visibly cleaner, faster, by filtering at low speed than by forcing the pump to the maximum—and incidentally, consuming a fraction of the energy.

This is why the NOXPLUS works most of the day at low speed: it is not only the most economical option but also the one that delivers better water quality. Medium and high speeds are reserved for specific moments that require greater flow—priming, pressurization, or surface skimming—as explained in the previous section.

Construction designed to last

MATERIALS

• Pump body, impeller, and diffuser in technopolymer
• Pump shaft in AISI 431 stainless steel
• Mechanical seal
• Motor casing in aluminum
• Gaskets in NBR/EPDM

MOTOR

• 2-pole asynchronous
• IPX5 protection
• Class F insulation
• Built-in thermal protection
• Suitable for continuous service

Compatible with saltwater up to 7 g/l and a maximum temperature of 40 °C, making it suitable for both traditional chlorine pools and salt systems. Includes 1.5 m of cable without a plug, 1½" unions, and a connection for a 40 mm hose—direct installation, no surprises.

Technical sheet

Model available in 230V (code 215306) · Weight: 12.8 kg

Renew your pool's filtration with less consumption

The NOXPLUS combines competitive pricing, virtually automatic setup, and measurable energy savings from the first electricity bill. Ideal for replacing single-speed pumps in small and medium residential pools.

Source: NOXPLUS technical data sheet, ESPA corporate catalog 2025 (60Hz).