S400
Limited evidenceRead the findings →The top corded robot in Dolphin's pool-shop S-line, with app control, a filter-full light and a caddy. It suits bigger pools and buyers who want app scheduling. It's sold mainly through pool shops, and its filter capacity in leafy pools is in doubt.
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Where it sits in Dolphin’s range
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What we know
Owners on Owners on Reddit say the S400 saves a lot of hand cleaning, while an owner on An owner on Trustpilot France with a 12 × 6 metre pool found the floor well cleaned but the walls and waterline less consistent. Robotic Reviews, a review site linked to a Dolphin dealer, says it cleaned its whole test pool from floor to waterline but rated its filter as bad; because of that link, we don't count it as independent. Specs come from Maytronics (global) and Maytronics (US).
Robotic Reviews, hands-on (tested on the Dolphin S400 (US in-store model); Site linked to a Dolphin dealer)
Less cleaning by hand
One owner on Owners on Reddit with a fairly small pool thought the S400 worth the money, and another said their routine had become much easier. A third liked how simple it was to handle compared with a suction cleaner hooked up to the pool equipment. None of them measured anything, so take this as general satisfaction rather than proof it cleans better than cheaper robots.
Walls and waterline: mixed reports
Maytronics (global) lists floor, wall and waterline cleaning with active scrubbing. Robotic Reviews says it covered its entire test pool up to the waterline and rated its waterline cleaning excellent. An owner on An owner on Trustpilot France, with a 12 × 6 metre concrete pool and a tiled band, found the floor well cleaned but the walls and waterline less consistent. Maytronics replied that it needed investigating, with no resolution shown. Bigger pools may be the harder test.
Filter: easy access, doubts on capacity
The multi-layer basket lifts out of the top, and a light warns when it's full, per Maytronics (global). The owner on An owner on Trustpilot France found the robot easy to clean, though the fine-filter panels took some practice. Robotic Reviews rated the filter as bad without saying why in its summary. It's a dealer-linked site, but if your pool gets heavy leaf fall, look at the basket size in a shop first.
App, timer and caddy
Over Wi-Fi, the MyDolphin Plus app sets schedules, sends notifications and lets you steer it by hand, per Maytronics (global). There's also a weekly timer and a delayed start, and a Retrieve Me mode brings it to the side when it has finished. The owner on An owner on Trustpilot France found set-up and the app straightforward. A caddy comes in the box, which pleased Robotic Reviews.
What's not checked yet
Nobody independent has published a hands-on test of the S400 yet. So the open questions are how it compares with rival robots, whether the basket copes with heavy leaf fall given the poor filter rating from Robotic Reviews, and whether the patchy wall and waterline cleaning the owner on An owner on Trustpilot France saw in a 12 × 6 metre pool is typical of bigger pools.
Our take
Should you buy the S400?
Best for: In-ground pools whose owners want scheduled cleaning from an app. Skip it if: You want a stronger record in independent tests before buying.
Consider it if you buy from a pool shop, want app control and a filter-full light and have a pool up to fifteen metres, knowing it hasn't been tested against rivals. The Nautilus CC Plus is the corded Dolphin with three independent reviews, and the Dolphin Liberty 600 covers the same pool size without a cable.
The S400 is the top of Dolphin's S-line, above the S200 and S300i, and is sold mainly through pool shops. It plugs into the mains, scrubs the floor, walls and waterline with an active brush, and connects over Wi-Fi to the MyDolphin Plus app for schedules and manual steering. Over the S300i it adds a light that tells you when the filter is full, a caddy and, in Europe, a rating for pools up to fifteen metres rather than twelve. It has a weekly timer and a swivel on the cable.
Robotic Reviews, a site linked to a Dolphin dealer, says it cleaned its whole test pool but rated its filter poorly. Owners like how much hand cleaning it saves, though their reports are short on detail, and one with a large pool found the walls and waterline less consistent. Everything else comes from Maytronics' listing.
Where to buy
Where to buy the S400 in United States
TC Pool Equipment Co
Best priceListed in stock
Marketplace · Delivery: check sellerSold by TC Pool Equipment Co. LLCSeller page ·InTheSwim Pool Supplies
Listed in stock
Dealer · Delivery: US$9.99 deliverySeller page ·Prices checked
We’re still looking for more United States retailers for this model.
Each price shows its source and check date. Prices are ordered by item price plus any stated delivery charge; delivery that needs a postcode or checkout check is not included. Confirm the final price and stock with the seller. Some links are affiliate links and are marked where they appear. Commission never changes the order or the recommendation.
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Price history
S400 price history in the US
Typical price Today's $1,499 is close to its $1,499 average since 3 Oct 2026.
- Today
- $1,499
- Lowest seen
- $1,4993 Oct 2026
- Average
- $1,499since 3 Oct 2026
Before you buy
The questions people ask about this one
Does it climb walls and clean the waterline?
Maytronics says yes, with active scrubbing, per the specifications. Robotic Reviews, a dealer-linked site, found full coverage in its test pool. An owner on An owner on Trustpilot France with a 12 × 6 metre pool found walls and the waterline cleaned less consistently than the floor.
Does it need an app?
No: a weekly timer and a delayed start are built in, per the specifications. The MyDolphin Plus app adds control from anywhere, schedules, notifications and manual steering over Wi-Fi. An owner on An owner on Trustpilot France found the app easy to set up.
How do you clean the filter?
Lift the multi-layer basket out of the top, unsnap the bottom and rinse it, per the specifications. A light tells you when it's full. The owner on An owner on Trustpilot France found the robot easy to clean but needed practice with the fine-filter panels.
How do I get it out of the water?
A Retrieve Me mode brings it to the side of the pool when it's done, per the specifications, and a caddy is included for moving it. It weighs 8.39kg dry, per Maytronics (global), and an owner on Owners on Reddit found it simple to handle.
Will it work in an above-ground pool?
Maytronics' US listing, per Maytronics (US), says in-ground and above-ground pools, but its European listing says in-ground only, per the specifications. None of the sources we use reports trying it in an above-ground pool, so check with your dealer.
Alternatives
Other robotic pool cleaners to compare.
Nautilus CC Plus
Why consider it: Three independent testers found this corded Dolphin cleans floors and walls quickly, with filters that are easy to empty.
The compromise: It sometimes sticks on steps, and testers disagree about whether it cleans the waterline.
LIBERTY 600
$250 more than the S400
Why consider it: Two testers found this cordless Dolphin leaves floors very clean, filters well and comes up when you shake the clicker.
The compromise: It wanders at random, and one tester found its step jet shifted only part of the dirt.
Premier
$500 more than the S400
Why consider it: A long-running corded Dolphin with a choice of filters, including a big leaf bag, and testers rate its waterline scrubbing highly.
The compromise: It has no app, and it's heavy to lift out.
Specs
Full specifications
Each specification names its source. Manufacturer claims are not independent test results; unconfirmed figures are labelled.
Owner reviews
Do you own the S400?
Tell people how it’s held up: cleaning, maintenance, faults and support. Owner accounts are shown separately from independent reviews.
Sources
Where this page’s findings come from
Editorial reviews
- Robotic Reviews: Dolphin S400 robotic pool cleaner review ↗73/100Hands-on · Tested on the Dolphin S400 (US in-store model) · Site linked to a Dolphin dealer (not counted towards our two-review minimum)
Sources
- Owners on Reddit: Are robot pool cleaners worth it? (r/swimmingpools) ↗Owner thread
- An owner on Trustpilot France: Maytronics France reviews, page 2 ↗Owner thread
- Maytronics (global): Dolphin S400 product page (99996261-EU) ↗Manufacturer
- Maytronics (US): Dolphin S400 product page (99996261-US) ↗Manufacturer
Videos
- Maytronics North America: Maytronics Dolphin S400 robotic pool cleaner top features ↗
- asiasi: Dolphin S400 Review: The Best Robotic Pool Cleaner? ↗
- Search YouTube for Dolphin S400 ↗Search results may include company demonstrations or similar models. Check the source and model name; a demonstration is not an independent performance test.