Sigma
Dolphin's top corded robot for US in-ground pools, with Wi-Fi app control and a gyroscope that keeps it on track. Testers found it cleans thoroughly, waterline included, but the app divides opinion and there's no leaf bag.
We re-check daily. Try the manufacturer’s site meanwhile.
The short version
The Sigma sits at the top of Dolphin's US corded range. It's 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 your home Wi-Fi so you can schedule, steer and check it from your phone. A swivel on the cable stops it twisting.
The trade-off is filtering and weight. 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's heavy to lift out, and a caddy costs extra.
Our take: Buy it for a large in-ground pool that mostly collects fine dirt, pollen and a scum line, if you want scheduling and remote control from your phone and your Wi-Fi reaches the pool. If leaves are your main problem, the cheaper Dolphin Premier has a proper leaf bag. If you'd rather not deal with a cable, look at the cordless Dolphin Liberty 600.
What we know so far
Limited evidence No independent, finished hands-on review of this robot yet. What follows comes from the maker's specifications and early coverage, and says where something is untested.
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. They split on the app: 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. The filters came out dark with 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. Expect it to handle a dirty pool in one go.
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. Robotic Reviews found it avoids going over the same area twice and stays pressed against walls and tiles rather than floating away. PoolPad liked how tightly it turns while keeping contact with the waterline. That means less time wasted 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 quoted by Robotic Reviews also say it 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. If your pool has a raised drain cover, budget for that brush.
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. Cleaning the top-loading cartridges is quick: The Pool Nerd puts it at about 30 seconds, and Robotic Reviews says routine servicing takes 10 to 15 minutes. At 24.6lb, Robotic Reviews found it heavy to lift out.
Prices
Where to buy the Sigma in United States
No verified United States price in the last 7 days. We re-check daily.
We’re still looking for more United States retailers for this model. Prices shown are read from each seller’s own page.
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 that's the main reason to pick it over the Premier. The app 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?
By lifting it out by hand. It weighs 24.63lb dry, per the specifications, and Robotic Reviews found it heavy to remove from the pool. A caddy for moving it around is sold separately.
How do I 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.
Compare with
LIBERTY 600
Two testers found this cordless Dolphin leaves floors very clean, filters well and comes up when you shake the clicker.
It wanders at random, and Les Numériques was critical of its app.
AquaSense 2 Ultra
Four testers rated its underwater cleaning highly, and its camera goes back for leaves it missed.
It's very heavy, and testers disagree about how well it skims.
Scuba X1 Pro Max
T3 and Heise rate its floor, wall and waterline cleaning among the best they've tested, and it skims too.
It weighs about 15kg, and Reviewed couldn't get it to finish runs reliably.
Full specifications
Figures come from the manufacturer’s product page unless a source is named. A blank means nobody we trust has confirmed it.
Owner reviews
Own a Sigma?
Tell people how it’s held up: cleaning, maintenance, faults and support. Owner reviews are shown separately from expert tests and never mixed into the score.
Sources
Everything cited on this page. Expert scores are shown as the reviewer gave them.
- 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)
- Maytronics (US): Dolphin Sigma product page (99991036-SPLI)Manufacturer