Help me choose
A stronger Pool Express option
Dolphin S50 and Dolphin Sigma are compared feature by feature below. For a stronger Pool Express option, consider Dolphin Cayman. Inground and above-ground pools up to 40 ft that need floor and wall cleaning.
ProLine
Dolphin Sigma
Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
What we recommend instead
Dolphin Cayman
Inground and above-ground pools up to 40 ft that need floor and wall cleaning.
$1,079
Buy Dolphin CaymanDolphin S50 or Dolphin Sigma: our take
Dolphin S50 and Dolphin Sigma 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 S50 is intended for above-ground pools, while Dolphin Sigma is intended for inground pools. Dolphin S50 is rated for pools up to 30 ft; Dolphin Sigma is rated up to 50 ft. Dolphin S50 cleans floor; Dolphin Sigma cleans floor, walls, and waterline. Dolphin S50 lists 1 active brush. Dolphin Sigma lists 2 active brushes, SmartNav 3.0 with gyroscope navigation, and Triple commercial-grade DC motors.
Filtration and debris
Dolphin S50 includes Basket; Dolphin Sigma includes Standard filter and NanoFilters. Dolphin Sigma has the clearer documented edge for fine silt, pollen and sand. Dolphin S50 also has the better documented path for bulky leaves and larger debris.
Controls and day-to-day ownership
Dolphin S50 provides one-touch starts and power-supply controls; Dolphin Sigma provides a weekly timer, smartphone control, and included remote control. Dolphin S50 uses a 40 ft corded cable, while Dolphin Sigma uses a 55 ft corded cable with an anti-tangle swivel. Dolphin S50 is listed at 14 lb versus 24.6 lb for Dolphin Sigma; that 10.600000000000001 lb difference matters when lifting the robot from the pool.
Price, warranty and the decision
Dolphin S50 is listed at $649 and Dolphin Sigma at $2,399; Dolphin S50 is $1,750 less. Dolphin S50 lists a 2-year warranty compared with 3 years for Dolphin Sigma. Dolphin S50 and Dolphin Sigma each have a specific fit, but neither is the Pool Express pick for this job. Our better alternative is Dolphin Cayman. Inground and above-ground pools up to 40 ft that need floor and wall cleaning.
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 S50 | Dolphin Sigma |
|---|---|---|
| Cleans the pool floor | Yes | Yes |
| Climbs and cleans walls | No | YesEdge |
| Scrubs the waterline | No | YesEdge |
| Fine-debris filter included | No | YesEdge |
| Large-debris filter | YesEdge | No |
| Automatic scheduling | No | YesEdge |
| Smartphone app | No | YesEdge |
| Anti-tangle swivel | Not listed | Yes |
| 3-year warranty | No | YesEdge |
| No recharging between cycles | Yes | Yes |
| 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 S50 stands out
Dolphin S50 is the better fit for shoppers prioritizing the lower $649 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $1,750 lower
- Weighs 14 lb versus 24.6 lb
Where Dolphin Sigma stands out
Dolphin Sigma is the better fit for pools up to 50 ft.
- Cleans the floor, walls and waterline instead of stopping below the tile line
- Includes filtration for sand, pollen and other fine debris
- Uses 2 active brushes instead of 1
- Can start on a weekly schedule without a manual launch before every cycle
Dolphin S50 vs Dolphin Sigma 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 S50 | Dolphin Sigma |
|---|---|---|
| Best fit | Above-ground pools up to 30 ft that need floor cleaning. | Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris. |
| Starting price | $649 | $2,399 |
| Pool type | Above-ground | Inground |
| Maximum pool length | Up to 30 ft | Up to 50 ft |
| Cleaning coverage | Floor | Floor, Walls, Waterline |
| Power | Corded | Corded |
| Filtration | Basket | Standard filter, NanoFilters |
| Scheduling | One-touch start | Weekly schedule + app |
| App and remote | Power-supply controls | App + included remote |
| Cable | 40 ft | 55 ft with anti-tangle swivel |
| Robot weight | 14 lb | 24.6 lb |
| Warranty | 2 years | 3 years |
Consider the stronger Pool Express option
Dolphin S50 and Dolphin Sigma are compared feature by feature below. For a stronger Pool Express option, consider Dolphin Cayman. Inground and above-ground pools up to 40 ft that need floor and wall cleaning.
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