Sigma
Limited evidenceRead the findings →The app-connected sibling of Dolphin's Premier, near the top of its US corded range. It suits large in-ground pools you want to schedule from your phone. Its app divides opinion, there's no leaf bag and no fully independent test.
Updated
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Where it sits in Dolphin’s range
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What we know
Three US reviewers ran it in real pools. Robotic Reviews let a pool go for days, then watched one cycle leave it virtually spotless. The Pool Nerd ran it daily for weeks, and PoolPad tested it for weeks too. All three sites are linked to a Dolphin dealer, so none counts as independent. All three rate its coverage and waterline cleaning. The app splits them: The Pool Nerd and PoolPad love it, while Robotic Reviews found it good rather than great. Robotic Reviews also relays owner reports of it getting stuck on main drains.
Robotic Reviews, hands-on (Site linked to a Dolphin dealer) · The Pool Nerd, hands-on, Weeks of daily runs, Jul 2026 (Site linked to a Dolphin dealer) · PoolPad, hands-on, Several weeks, Feb 2026 (Site linked to a Dolphin dealer)
Thorough cleaning, waterline included
Robotic Reviews let leaves, buds, pollen and bugs build up for several days, and after one 2.5-hour cycle the pool was virtually spotless, with the filters dark from fine dirt and algae. PoolPad scored its coverage 10 out of 10 and said the waterline had never been cleaner. The Pool Nerd credits its float handle with helping it climb and scrub up to the tile line. These are encouraging accounts from dealer-linked sites, not a promise that every dirty pool will be clean in one cycle.
Straight lines, not random wandering
The gyroscope is the big difference from cheaper Dolphins. The Pool Nerd saw it clean in deliberate, methodical passes without missing patches. It avoids going over the same area twice, Robotic Reviews found, and stays pressed against walls and tiles rather than floating away. PoolPad liked how tightly it turns while keeping contact with the waterline. So less time goes on areas it has already done.
The app splits the reviewers
The Pool Nerd and PoolPad both rate the app highly for scheduling, wall-only cleaning, manual steering and voice control. Robotic Reviews called it good but not great, and warned it may frustrate people who aren't comfortable with tech. Owners it quotes also say the app sometimes has to be closed and reopened before it connects. If your Wi-Fi is weak at the poolside, test it there before relying on the app.
Main drains can trap it
Owner reviews quoted by Robotic Reviews describe it getting stuck on top of the main drain and needing to be pulled free. The Pool Nerd tested it with Dolphin's newer oscillating centre brush, which is sold separately, and had no hang-ups in weeks of daily runs. That's not a controlled comparison, so it doesn't prove the optional brush stops it catching on a raised drain. Check it suits your drain cover before paying for it.
Fine dirt yes, heavy leaves no
There's no leaf bag. PoolPad marked it down slightly for that and pointed to the Premier, which has one. Owners quoted by Robotic Reviews say heavy loads of debris can clog it. The top-loading cartridges are quick to clean: The Pool Nerd puts it at about 30 seconds, and Robotic Reviews says routine servicing takes 10 to 15 minutes. At 24.6lb, it felt heavy to lift out for Robotic Reviews.
Our take
Should you buy the Sigma?
Best for: Pools where sand, pollen and fine dirt are the main problem. Skip it if: Wi-Fi does not reach your pool.
The Sigma may suit a large in-ground pool if you want phone scheduling, Wi-Fi reaches the pool and you can manage an approximately 11kg dry lift. Its cleaning accounts are all dealer-linked, and app experiences vary. Confirm the filter kit in the exact SKU. The Premier offers a leaf bag; the cordless Liberty 600 removes the cable but has its own routing and app limitations.
The Sigma sits toward the top of Dolphin's US corded range as the Premier's app-connected sibling. It cleans the floor, walls and waterline on a two-and-a-half-hour cycle, uses a gyroscope to plan straight, methodical passes, and connects to home Wi-Fi so you can schedule, steer and check it from your phone. A swivel is intended to reduce cable twisting.
The three hands-on accounts come from sites linked to a Dolphin dealer, rather than independent reviewers. Robotic Reviews let a pool go for days and watched one cycle leave it virtually spotless, The Pool Nerd ran it daily for weeks and PoolPad also tested it, and they found it cleans thoroughly, waterline included, though the app divided them. From Maytronics' listing, it comes with fine and ultra-fine cartridges that load from the top but no leaf bag, so a pool buried in leaves will fill it fast. At about 11kg dry it is heavy to lift out, a caddy costs extra,.
Before you buy
The questions people ask about this one
Does it climb walls and clean the waterline?
Yes, it's built for the floor, walls and waterline, per the specifications. Robotic Reviews found the gyroscope keeps it pressed against walls so it cleans the tiles and waterline accurately, and PoolPad said its waterline had never been cleaner.
Does it need an app?
No, but the app is the main reason to pick it over the Premier. It handles scheduling, remote steering and cleaning stats over Wi-Fi, per the specifications. The Pool Nerd and PoolPad rated it highly, while Robotic Reviews found it good rather than great and relays owner reports of dropped connections.
Does it handle leaves as well as fine dirt?
Fine dirt, yes: Robotic Reviews found the filters dark with fine dirt and algae after one cycle. Leaves are its weaker side, because there's no leaf bag, as PoolPad points out. Owners quoted by Robotic Reviews say large amounts of debris can clog it.
How do I get it out of the water?
You lift it out by hand. It weighs 24.63lb dry, per the specifications, and Robotic Reviews found it heavy to get out of the pool. A caddy for moving it around is sold separately.
How do you clean the filter?
The cartridges load from the top, per the specifications, so you lift them out without turning the robot over and hose them down. The Pool Nerd says it takes about 30 seconds, and Robotic Reviews puts routine servicing at 10 to 15 minutes.
Alternatives
Other robotic pool cleaners to compare.
LIBERTY 600
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 Les Numériques was critical of its app.
AquaSense 2 Ultra
Why consider it: Testers rated its underwater cleaning highly, and its camera searches for missed leaves on the pool floor.
The compromise: It's very heavy, and testers disagree about how well it skims.
Scuba X1 Pro Max
Why consider it: T3 and Heise rate its floor, wall and waterline cleaning among the best they've tested, and it skims too.
The compromise: It weighs about 15kg, and Reviewed couldn't get it to finish runs reliably.
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 Sigma?
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 Sigma robotic pool cleaner review ↗98/100Hands-on · Site linked to a Dolphin dealer (not counted towards our two-review minimum)
- The Pool Nerd: Dolphin Sigma review ↗Pool Nerd ApprovedHands-on, Weeks of daily runs · Site linked to a Dolphin dealer (not counted towards our two-review minimum)
- PoolPad: Dolphin Sigma review ↗9.8/10Hands-on, Several weeks · Site linked to a Dolphin dealer (not counted towards our two-review minimum)
Sources
Videos
- Search YouTube for Dolphin Sigma ↗Search results may include company demonstrations or similar models. Check the source and model name; a demonstration is not an independent performance test.