Help me choose
Our pick: Dolphin Sigma
Dolphin Sigma is the Pool Express pick in this matchup. Dolphin Sigma cleans the floor, walls and waterline instead of stopping below the tile line. Dolphin Sigma includes filtration for sand, pollen and other fine debris.
Max-Series
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.
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 Cayman or Dolphin Sigma: our take
Dolphin Cayman 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 Cayman is intended for inground and above-ground pools, while Dolphin Sigma is intended for inground pools. Dolphin Cayman is rated for pools up to 40 ft; Dolphin Sigma is rated up to 50 ft. Dolphin Cayman cleans floor and walls; Dolphin Sigma cleans floor, walls, and waterline. Dolphin Cayman lists 1 active brush, SmartNav 2.0 navigation, and Dual 24-volt DC motors. Dolphin Sigma lists 2 active brushes, SmartNav 3.0 with gyroscope navigation, and Triple commercial-grade DC motors.
Filtration and debris
Dolphin Cayman includes MaxBin; Dolphin Sigma includes Standard filter and NanoFilters. Dolphin Sigma has the clearer documented edge for fine silt, pollen and sand. Dolphin Cayman also has the better documented path for bulky leaves and larger debris.
Controls and day-to-day ownership
Dolphin Cayman provides a weekly timer and power-supply controls; Dolphin Sigma provides a weekly timer, smartphone control, and included remote control. Dolphin Cayman uses a 50 ft corded cable, while Dolphin Sigma uses a 55 ft corded cable with an anti-tangle swivel. Dolphin Cayman is listed at 14.6 lb versus 24.6 lb for Dolphin Sigma; that 10.000000000000002 lb difference matters when lifting the robot from the pool.
Price, warranty and the decision
Dolphin Cayman is listed at $1,079 and Dolphin Sigma at $2,399; Dolphin Cayman is $1,320 less. Dolphin Cayman lists a 2-year warranty compared with 3 years for Dolphin Sigma. Pool Express pick: Dolphin Sigma. Dolphin Sigma cleans the floor, walls and waterline instead of stopping below the tile line. Dolphin Sigma includes filtration for sand, pollen and other fine debris. Choose Dolphin Cayman when it is the better fit for shoppers prioritizing the lower $1,079 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 Cayman | Dolphin Sigma |
|---|---|---|
| Cleans the pool floor | Yes | Yes |
| Climbs and cleans walls | Yes | Yes |
| Scrubs the waterline | No | YesEdge |
| Fine-debris filter included | No | YesEdge |
| Large-debris filter | YesEdge | No |
| Automatic scheduling | Yes | Yes |
| Smartphone app | No | YesEdge |
| Anti-tangle swivel | No | YesEdge |
| 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 Cayman stands out
Dolphin Cayman is the better fit for shoppers prioritizing the lower $1,079 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $1,320 lower
- Weighs 14.6 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
- Uses a triple-motor cleaning system
Dolphin Cayman 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 Cayman | Dolphin Sigma |
|---|---|---|
| Best fit | Inground and above-ground pools up to 40 ft that need floor and wall cleaning. | Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris. |
| Starting price | $1,079 | $2,399 |
| Pool type | Inground, Above-ground | Inground |
| Maximum pool length | Up to 40 ft | Up to 50 ft |
| Cleaning coverage | Floor, Walls | Floor, Walls, Waterline |
| Power | Corded | Corded |
| Filtration | MaxBin | Standard filter, NanoFilters |
| Scheduling | Weekly schedule | Weekly schedule + app |
| App and remote | Power-supply controls | App + included remote |
| Cable | 50 ft | 55 ft with anti-tangle swivel |
| Robot weight | 14.6 lb | 24.6 lb |
| Warranty | 2 years | 3 years |
Choose Dolphin Sigma
Dolphin Sigma is the Pool Express pick in this matchup. Dolphin Sigma cleans the floor, walls and waterline instead of stopping below the tile line. Dolphin Sigma includes filtration for sand, pollen and other fine debris.
More robotic pool cleaner comparisons
Keep comparing without rebuilding the same specification table yourself.
Clear UV vs Clear S
Pool Express pick: Clear UV
Dolphin Quantum vs Clear S
Pool Express pick: Dolphin Quantum
Dolphin Premier vs Dolphin Sigma
Pool Express pick: Dolphin Premier
Dolphin Premier vs Dolphin Quantum
Pool Express pick: Dolphin Quantum
Dolphin Sigma vs Dolphin Quantum
Pool Express pick: Dolphin Quantum
Dolphin Cayman vs Dolphin Escape
Pool Express pick: Dolphin Cayman