Help me choose
A stronger Pool Express option
Dolphin M400 and Niya Tracker 55 are compared feature by feature below. For a stronger Pool Express option, consider Dolphin Quantum. Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
M-Line
Dolphin M400
Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
Niya Tracker
Niya Tracker 55
Inground and above-ground pools up to 40 ft that need floor, wall and waterline cleaning without a cord, with app-selected modes.
What we recommend instead
Dolphin Quantum
Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
$1,649
Buy Dolphin QuantumDolphin M400 or Niya Tracker 55: our take
Dolphin M400 and Niya Tracker 55 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 M400 is intended for inground pools, while Niya Tracker 55 is intended for inground and above-ground pools. Dolphin M400 is rated for pools up to 50 ft; Niya Tracker 55 is rated up to 40 ft. Each cleans floor, walls, and waterline, so coverage alone does not separate them. Niya Tracker 55's documented cleaning system includes 2 active brushes, Sonar navigation, and Dual drive motors.
Filtration and debris
Dolphin M400 includes Standard filter and UltraFilter; Niya Tracker 55 includes Basket. That gives Dolphin M400 the clearer documented edge for fine silt, pollen and sand. Niya Tracker 55 has the better documented path for bulky leaves and larger debris.
Controls and day-to-day ownership
Dolphin M400 provides smartphone control; Niya Tracker 55 provides one-touch starts and smartphone control. Dolphin M400 uses a 60 ft corded cable with an anti-tangle swivel, while Niya Tracker 55 uses cordless battery power.
Price, warranty and the decision
Dolphin M400 is listed at $1,599 and Niya Tracker 55 at $779; Niya Tracker 55 is $820 less. Dolphin M400 lists a 3-year warranty compared with 1.5 years for Niya Tracker 55. Dolphin M400 and Niya Tracker 55 each have a specific fit, but neither is the Pool Express pick for this job. Our better alternative is Dolphin Quantum. Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
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 M400 | Niya Tracker 55 |
|---|---|---|
| Cleans the pool floor | Yes | Yes |
| Climbs and cleans walls | Yes | Yes |
| Scrubs the waterline | Yes | Yes |
| Fine-debris filter included | YesEdge | No |
| Large-debris filter | No | YesEdge |
| Automatic scheduling | Not listed | No |
| 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 M400 stands out
Dolphin M400 is the better fit for pools up to 50 ft.
- Includes filtration for sand, pollen and other fine debris
- Carries a 3-year warranty instead of 1.5 years
- Is rated for pools up to 50 ft
- Runs from continuous plug-in power without a recharge between cycles
Where Niya Tracker 55 stands out
Niya Tracker 55 is the better fit for shoppers prioritizing the lower $779 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $820 lower
Dolphin M400 vs Niya Tracker 55 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 M400 | Niya Tracker 55 |
|---|---|---|
| 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 40 ft that need floor, wall and waterline cleaning without a cord, with app-selected modes. |
| Starting price | $1,599 | $779 |
| Pool type | Inground | Inground, Above-ground |
| Maximum pool length | Up to 50 ft | Up to 40 ft |
| Cleaning coverage | Floor, Walls, Waterline | Floor, Walls, Waterline |
| Power | Corded | Cordless |
| Filtration | Standard filter, UltraFilter | Basket |
| Scheduling | Not listed | One-touch start |
| App and remote | App control | App control |
| Cable | 60 ft with anti-tangle swivel | Cordless |
| Robot weight | Not listed | 19.8 lb |
| Warranty | 3 years | 1.5 years |
Consider the stronger Pool Express option
Dolphin M400 and Niya Tracker 55 are compared feature by feature below. For a stronger Pool Express option, consider Dolphin Quantum. Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.
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