Robotic pool cleaner comparison

Dolphin S300 vs Dolphin T35

A side-by-side comparison of pool fit, cleaning coverage, filtration, controls and the better Pool Express option.

By Brian Williamson, Pool Express product specialist
Updated November 9, 2026

Better alternative

A stronger Pool Express option

Dolphin S300 and Dolphin T35 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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S-Line

Dolphin S300

Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.

Listed price $1,499

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T-Line

Dolphin T35

Inground pools that need floor, wall and waterline cleaning, with fine debris.

Listed price $1,199

View better alternatives

A better alternative

What we recommend instead

Pool Express pick

Dolphin Quantum

Inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.

$1,649

Buy Dolphin Quantum

Buying guidance

Dolphin S300 or Dolphin T35: our take

Dolphin S300 and Dolphin T35 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 S300 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 S300's documented cleaning system includes 2 active brushes and CleverClean navigation.

Filtration and debris

Both models include Basket and UltraFilter. Both have documented fine-debris media, so basket capacity and ease of cleaning matter more than fine-particle capability.

Controls and day-to-day ownership

Both models provide a weekly timer and smartphone control. Both use a 60 ft corded cable with an anti-tangle swivel.

Price, warranty and the decision

Dolphin S300 is listed at $1,499 and Dolphin T35 at $1,199; Dolphin T35 is $300 less. Each lists a 2-year manufacturer warranty. Dolphin S300 and Dolphin T35 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 S300	Dolphin T35
Cleans the pool floor	Yes	Yes
Climbs and cleans walls	Yes	Yes
Scrubs the waterline	Yes	Yes
Fine-debris filter included	Yes	Yes
Large-debris filter	Yes	Yes
Automatic scheduling	Yes	Yes
Smartphone app	Yes	Yes
Anti-tangle swivel	Yes	Yes
3-year warranty	No	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 S300 stands out

Dolphin S300 is the better fit for inground pools up to 50 ft that need floor, wall and waterline cleaning, with fine debris.

Where Dolphin T35 stands out

Dolphin T35 is the better fit for shoppers prioritizing the lower $1,199 starting price.

Is listed $300 lower