Help me choose
A stronger Pool Express option
Dolphin Sigma and Niya Sonar 20 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.
Niya Sonar
Niya Sonar 20
Above-ground pools up to 26 ft that need the floor cleaned without a cord.
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 Sigma or Niya Sonar 20: our take
Dolphin Sigma and Niya Sonar 20 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 Niya Sonar 20 is intended for above-ground pools. Dolphin Sigma is rated for pools up to 50 ft; Niya Sonar 20 is rated up to 26 ft. Dolphin Sigma cleans floor, walls, and waterline; Niya Sonar 20 cleans floor. Dolphin Sigma lists 2 active brushes, SmartNav 3.0 with gyroscope navigation, and Triple commercial-grade DC motors. Niya Sonar 20 lists Sonar navigation and Dual drive motors.
Filtration and debris
Dolphin Sigma includes Standard filter and NanoFilters; Niya Sonar 20 includes Basket. That gives Dolphin Sigma the clearer documented edge for fine silt, pollen and sand. Niya Sonar 20 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; Niya Sonar 20 provides one-touch starts and power-supply controls. Dolphin Sigma uses a 55 ft corded cable with an anti-tangle swivel, while Niya Sonar 20 uses cordless battery power. Dolphin Sigma is listed at 24.6 lb versus 10 lb for Niya Sonar 20; that 14.600000000000001 lb difference matters when lifting the robot from the pool.
Price, warranty and the decision
Dolphin Sigma is listed at $2,399 and Niya Sonar 20 at $199; Niya Sonar 20 is $2,200 less. Dolphin Sigma lists a 3-year warranty compared with 1 years for Niya Sonar 20. Dolphin Sigma and Niya Sonar 20 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 Sigma | Niya Sonar 20 |
|---|---|---|
| Cleans the pool floor | Yes | Yes |
| Climbs and cleans walls | YesEdge | No |
| Scrubs the waterline | YesEdge | No |
| Fine-debris filter included | YesEdge | No |
| Large-debris filter | No | YesEdge |
| Automatic scheduling | YesEdge | No |
| Smartphone app | YesEdge | No |
| 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 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 a triple-motor cleaning system
- Adds gyroscope-assisted navigation
Where Niya Sonar 20 stands out
Niya Sonar 20 is the better fit for shoppers prioritizing the lower $199 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $2,200 lower
- Weighs 10 lb versus 24.6 lb
Dolphin Sigma vs Niya Sonar 20 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 | Niya Sonar 20 |
|---|---|---|
| Best fit | Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris. | Above-ground pools up to 26 ft that need the floor cleaned without a cord. |
| Starting price | $2,399 | $199 |
| Pool type | Inground | Above-ground |
| Maximum pool length | Up to 50 ft | Up to 26 ft |
| Cleaning coverage | Floor, Walls, Waterline | Floor |
| Power | Corded | Cordless |
| Filtration | Standard filter, NanoFilters | Basket |
| Scheduling | Weekly schedule + app | One-touch start |
| App and remote | App + included remote | Power-supply controls |
| Cable | 55 ft with anti-tangle swivel | Cordless |
| Robot weight | 24.6 lb | 10 lb |
| Warranty | 3 years | 1 years |
Consider the stronger Pool Express option
Dolphin Sigma and Niya Sonar 20 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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