Help me choose
Our pick: Dolphin Sigma
Dolphin Sigma is the Pool Express pick in this matchup. Dolphin Sigma adds gyroscope-assisted navigation. Dolphin Sigma carries a 3-year warranty instead of 1 years.
ProLine
Dolphin Sigma
Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
EON
Dolphin Nautilus EON 120d
Inground and above-ground pools up to 50 ft that need whole-pool cordless cleaning with the least filter maintenance.
Why Dolphin Sigma is our pick
Dolphin Sigma
Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
$2,399
Buy Dolphin SigmaDolphin Sigma or Dolphin Nautilus EON 120d: our take
Dolphin Sigma and Dolphin Nautilus EON 120d are compared on pool fit, cleaning reach, debris handling, controls and ownership details. The recommendation is based on the job the robot must do—not a simple feature count.
Pool fit and cleaning reach
Dolphin Sigma is intended for inground pools, while Dolphin Nautilus EON 120d is intended for inground and above-ground pools. Both are rated for pools up to 50 ft. Each cleans floor, walls, and waterline, so coverage alone does not separate them. Dolphin Sigma lists 2 active brushes, SmartNav 3.0 with gyroscope navigation, and Triple commercial-grade DC motors. Dolphin Nautilus EON 120d lists 2 active brushes and SmartMap navigation.
Filtration and debris
Dolphin Sigma includes Standard filter and NanoFilters; Dolphin Nautilus EON 120d includes Basket and UltraFilter. Both have documented fine-debris media, so basket capacity and ease of cleaning matter more than fine-particle capability. Dolphin Nautilus EON 120d has the better documented path for bulky leaves and larger debris.
Controls and day-to-day ownership
Dolphin Sigma provides a weekly timer, smartphone control, and included remote control; Dolphin Nautilus EON 120d provides a weekly timer and smartphone control. Dolphin Sigma uses a 55 ft corded cable with an anti-tangle swivel, while Dolphin Nautilus EON 120d uses cordless battery power. Dolphin Sigma is listed at 24.6 lb versus 24.3 lb for Dolphin Nautilus EON 120d; that 0.3000000000000007 lb difference matters when lifting the robot from the pool.
Price, warranty and the decision
Dolphin Sigma is listed at $2,399 and Dolphin Nautilus EON 120d at $1,199; Dolphin Nautilus EON 120d is $1,200 less. Dolphin Sigma lists a 3-year warranty compared with 1 years for Dolphin Nautilus EON 120d. Pool Express pick: Dolphin Sigma. Dolphin Sigma adds gyroscope-assisted navigation. Dolphin Sigma carries a 3-year warranty instead of 1 years. Choose Dolphin Nautilus EON 120d when it is the better fit for shoppers prioritizing the lower $1,199 starting price.
Feature check: what each robot actually has
A green check means the feature is documented as included. A red X means it is documented as absent. A dash means the source does not make the feature clear.
| Feature | Dolphin Sigma | Dolphin Nautilus EON 120d |
|---|---|---|
| Cleans the pool floor | Yes | Yes |
| Climbs and cleans walls | Yes | Yes |
| Scrubs the waterline | Yes | Yes |
| Fine-debris filter included | Yes | Yes |
| Large-debris filter | No | YesEdge |
| Automatic scheduling | Yes | Yes |
| Smartphone app | Yes | Yes |
| Anti-tangle swivel | Yes | Not listed |
| 3-year warranty | YesEdge | No |
| No recharging between cycles | YesEdge | No |
| Built-in UV-C water treatment | No | No |
Unknown is not treated as “no.” Specifications come from the product pages, current catalog records and manufacturer material collected for this site.
Where Dolphin Sigma stands out
Dolphin Sigma is the better fit for inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
- Adds gyroscope-assisted navigation
- Carries a 3-year warranty instead of 1 years
- Runs from continuous plug-in power without a recharge between cycles
Where Dolphin Nautilus EON 120d stands out
Dolphin Nautilus EON 120d is the better fit for shoppers prioritizing the lower $1,199 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $1,200 lower
- Weighs 24.3 lb versus 24.6 lb
Dolphin Sigma vs Dolphin Nautilus EON 120d specifications
Use pool fit first. Price and app control do not make up for a robot that cannot cover the length or surfaces you need cleaned.
| Specification | Dolphin Sigma | Dolphin Nautilus EON 120d |
|---|---|---|
| Best fit | Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris. | Inground and above-ground pools up to 50 ft that need whole-pool cordless cleaning with the least filter maintenance. |
| Starting price | $2,399 | $1,199 |
| Pool type | Inground | Inground, Above-ground |
| Maximum pool length | Up to 50 ft | Up to 50 ft |
| Cleaning coverage | Floor, Walls, Waterline | Floor, Walls, Waterline |
| Power | Corded | Cordless |
| Filtration | Standard filter, NanoFilters | Basket, UltraFilter |
| Scheduling | Weekly schedule + app | Weekly schedule + app |
| App and remote | App + included remote | App control |
| Cable | 55 ft with anti-tangle swivel | Cordless |
| Robot weight | 24.6 lb | 24.3 lb |
| Warranty | 3 years | 1 years |
Choose Dolphin Sigma
Dolphin Sigma is the Pool Express pick in this matchup. Dolphin Sigma adds gyroscope-assisted navigation. Dolphin Sigma carries a 3-year warranty instead of 1 years.
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