Help me choose
A stronger Pool Express option
Dolphin M400 and Dolphin Proteus DX4 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.
Proteus
Dolphin Proteus DX4
Inground pools that need floor, wall and waterline cleaning.
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 Dolphin Proteus DX4: our take
Dolphin M400 and Dolphin Proteus DX4 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
Both robots are intended for inground pools. Dolphin M400 has a published maximum pool length of 50 ft; the other model does not have a verified length in our source material. Each cleans floor, walls, and waterline, so coverage alone does not separate them. Dolphin Proteus DX4's documented cleaning system includes 1 active brush.
Filtration and debris
Dolphin M400 includes Standard filter and UltraFilter; Dolphin Proteus DX4 includes Basket. That gives Dolphin M400 the clearer documented edge for fine silt, pollen and sand. Dolphin Proteus DX4 has the better documented path for bulky leaves and larger debris.
Controls and day-to-day ownership
Dolphin M400 provides smartphone control; Dolphin Proteus DX4 provides a weekly timer and power-supply controls. Both use a 60 ft corded cable with an anti-tangle swivel.
Price, warranty and the decision
Dolphin M400 is listed at $1,599 and Dolphin Proteus DX4 at $1,199; Dolphin Proteus DX4 is $400 less. Dolphin M400 lists a 3-year warranty compared with 2 years for Dolphin Proteus DX4. Dolphin M400 and Dolphin Proteus DX4 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 | Dolphin Proteus DX4 |
|---|---|---|
| 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 | Yes |
| Smartphone app | YesEdge | No |
| Anti-tangle swivel | Yes | Yes |
| 3-year warranty | YesEdge | No |
| 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 M400 stands out
Dolphin M400 is the better fit for owners who put smartphone control first.
- Includes filtration for sand, pollen and other fine debris
- Adds smartphone control
- Carries a 3-year warranty instead of 2 years
Where Dolphin Proteus DX4 stands out
Dolphin Proteus DX4 is the better fit for shoppers prioritizing the lower $1,199 starting price.
- Includes a large-debris bin or bag for leaves
- Is listed $400 lower
Dolphin M400 vs Dolphin Proteus DX4 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 | Dolphin Proteus DX4 |
|---|---|---|
| Best fit | Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris. | Inground pools that need floor, wall and waterline cleaning. |
| Starting price | $1,599 | $1,199 |
| Pool type | Inground | Inground |
| Maximum pool length | Up to 50 ft | Not listed |
| Cleaning coverage | Floor, Walls, Waterline | Floor, Walls, Waterline |
| Power | Corded | Corded |
| Filtration | Standard filter, UltraFilter | Basket |
| Scheduling | Not listed | Weekly schedule |
| App and remote | App control | Power-supply controls |
| Cable | 60 ft with anti-tangle swivel | 60 ft with anti-tangle swivel |
| Robot weight | Not listed | Not listed |
| Warranty | 3 years | 2 years |
Consider the stronger Pool Express option
Dolphin M400 and Dolphin Proteus DX4 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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