Dolphin Sigma Review

This is the new Dolphin Sigma. It has a massive 10-inch cleaning path, and in my underwater manometer testing, it pulled over 2.0 PSI. That makes it one of the most powerful pool cleaners I’ve ever tested. Today, I’m showing you the data, the dirt, and exactly why the cordless robots all over your feed still can’t match this.

Hey guys, I’m Ryan with ActuallyUsed, where we put the products to the test so you don’t have to.

Pool robot brands love to quote GPH — gallons per hour. I quote PSI, because that’s what my manometer reads at the intake port, and those two numbers measure very different things. Later in this review, I’ll show you exactly why the battery-powered units are failing to hit these numbers, but first, let’s look at the new Sigma, the 2.0 PSI it posted in my pool, and whether it deserves a spot in yours.

How I Test (and Why PSI, Not GPH)

Quick refresher on how I test, because this is what separates ActuallyUsed from the spec-sheet reviews. Every robot runs in this pool for weeks — not a day, not a weekend. And for suction, I hook a hydro manometer directly to the intake port and measure PSI underwater. As far as I know, we started this test for pool robots, and it’s still the number nobody else shows you.

Here’s why it matters. Manufacturers publish GPH — how many gallons per hour move through the pump. That’s a flow number, and it’s fine for what it is. PSI at the port measures pull — how hard the robot grabs debris off your floor. Both numbers are real; they just answer different questions. A robot with a huge GPH figure can still post a modest PSI on my gauge, which is exactly why I measure it myself.

At this point, my logbook covers manometer readings on more than two dozen robots, plus tape-measured intake ports on over 40. So when I tell you a robot is good, it’s not just a feeling.

What’s New on the Sigma This Year

Dolphin didn’t reinvent the Sigma — they sharpened it. Four updates stood out in my testing:

• An upgraded center brush that keeps steadier scrubbing contact on the floor, walls, and waterline.
• NanoFilters — the ultra-fine pleated cartridges that grab the silt and algae-sized particles most robots push around. They’re the best of the best when it comes to robot filtration, as most robots just have mesh.
• A gyroscope feeding the SmartNav system, which shows up as straighter lanes and fewer missed strips.
• Triple the warranty coverage of most robots I’ve reviewed. You get a 3-year warranty, compared to the popular Dolphin Nautilus or other cordless robots that only come with a 1-year warranty.

None of these is flashy on its own. Stacked on top of the three commercial-grade motors this robot already had, they add up to the most complete Sigma yet.

The Headline Number: 2.0 PSI

Let’s get to the test. With the manometer sealed on the intake port, the Sigma pulled exactly 2.0 PSI.

Here is where that lands on my overall leaderboard so you can see the comparison. (Note: all tests are my independent tests in the same pool; your results may vary):

Starting from the strongest suction I measured: the Dolphin Premier came in first at 2.2 PSI, followed by the Clear UV at 2.09, the Dolphin Sigma at 2.0, and the Dolphin Quantum Pro at 1.9. After that there was a cluster around 1.5 PSI, including the Beatbot AquaSense 2 Pro, Dolphin Cayman, and Dolphin Escape. The Wybot C2 was just behind at 1.49 PSI, followed by the Aiper X1 Pro Max at 1.3, the Dolphin Liberty 200 at 1.23, both the Beatbot AquaSense 2 Ultra and Dolphin Nautilus CC at 1.2, and finally the Aiper X1 Pro at 1.0 PSI.

Full transparency, because that’s the whole point of this channel: the Sigma is not the single highest number I’ve ever logged. Exactly two robots have beaten it. The Dolphin Premier hit 2.2 PSI, and the brand new Clear UV posted 2.09 PSI.

But look at the rest of that chart. Nothing from the cordless crowd — Beatbot, Aiper, Polaris Freedom, Wybot, even Dolphin’s own Liberty — has matched it. The strongest battery-powered reading in my logbook is 1.6, and most of the big names land between 1.0 and 1.6. The top of my leaderboard is all corded, and the Sigma sits square in that top tier.

In the pool, that pull is visible. Fine sand, algae dust, waterlogged leaves — in my testing, the Sigma grabs them on the first pass instead of pushing a little bow wave of debris around the floor.

The 10-Inch Intake Path

Suction is half the equation. The other half is how wide a bite the robot takes on every pass — and since almost nobody measures that spec, I did. Tape measure, more than 40 robots.

The Sigma runs two intake ports at five inches each: ten inches of total intake path. The average port in my dataset is right around six inches wide. That’s why I said the Sigma’s intake is more than 50% wider than the average port I’ve measured.

When it comes to intake width, bigger generally means the robot can pick up leaves and debris more efficiently in a single pass. The clear winner here is the Dolphin Sigma, with two 5-inch intake ports for a total of 10 inches. The Dolphin Premier is close behind at 9.5 inches. Next are the Dolphin Quantum Pro and Wybot C2 with 7-inch intakes, followed by the Beatbot AquaSense 2 Ultra and Dolphin Explorer E70 at 6.5 inches. The Aiper X1 Pro Max measures just over 6 inches, while the Dolphin Cayman rounds out the list with a 5-inch intake.

Why does width matter? Coverage math. A wider path means fewer passes to sweep the same floor, and fewer chances for a leaf to skate past the port on a turn. Pair ten inches of intake with 2.0 PSI of pull and, in my experience, you get first-pass pickup — the robot isn’t circling back for debris it missed the first time.

Corded vs. Cordless: What My Data Keeps Showing

There’s a lot of marketing behind cordless robots right now, and I get the appeal — no cable looks clean in an ad. But after testing both types side by side, the corded Sigma keeps winning on the things that decide whether your pool is actually clean. Here’s the case.

• Consistent power: A cord delivers constant wall power to the Sigma’s three commercial-grade motors for the entire cycle. A cordless robot has to budget a battery. My theory — and it’s the same thing you’ve felt with a cordless stick vacuum at home — is that battery-powered suction has a ceiling, and my manometer keeps backing that up. No battery-powered robot in my logbook has hit 2.0 PSI. Now, how much does a cordless robot fade across a full charge? That’s exactly what my battery drain-down test is built to measure. I’m running it right now, so subscribe if you want those numbers the day they’re ready.
• The daily routine: This is what wore me out testing the cordless robots all over your feed. Every single day: fish the robot out, carry a dripping unit across the deck to an outlet, charge it for hours, then walk it back and drop it in. Call it 14 separate interactions a week. The Sigma? One. I rinse the filters once a week, and that’s the whole relationship.
• Longer cycles: Most cordless robots I’ve tested run 60 to 90 minutes before they need the charger. The Sigma’s standard cycle is 2.5 hours — and because it’s on wall power, you can run it again back-to-back after a storm dumps half a tree in your pool. More runtime, more thorough cleaning, zero downtime.

Filtration: The Top-Load NanoFilters

The top-loading filter system might be my favorite thing about owning this robot. Most pool robots make you flip the entire unit upside down to get at the filters. On the Sigma, you pop the top, lift the cartridges straight out, rinse, done. No dripping water across the deck, no wrestling a heavy robot onto its back. Seriously — why didn’t someone think of this sooner?

You also get two filtration setups: NanoFilters for the ultra-fine stuff — algae, silt, fine sand — and standard cartridges for everyday leaves and grit. In my experience, pleated cartridges like these out-filter the mesh baskets a lot of robots ship with. Finer media, more rigid structure, more surface area — so debris stays trapped instead of washing back into the pool.

And the amount of junk these cartridges pull out of a clear-looking pool still surprises me. They come out packed — dirt, leaves, algae, the works.

AutoStart + the Weekly Smart Timer

This is where the Sigma runs away from the cordless crowd for me. Set the schedule once — in the app or on the power supply — and AutoStart wakes the robot up to clean on the days you picked. No recharging, no babysitting, no remembering. Drop it in Monday, rinse the filters Sunday. That’s full pool-cleaning automation, and it only works because the power never runs out.

Active Center Brush

Now this is the newest update for the year, the Active Center Brush. It snaps in and adds more scrubbing power to your Sigma. The best part is if your robot gets stuck on a drain – the Dolphin Sigma now fixes that. By adding the center brush, the Sigma will never get hung up on main drains.

After testing so many cleaners, you find out this happens a lot on almost every model from every brand. If you don’t want to shell out the extra cash for the brush, keep an eye on ActuallyUsed.com/Robot-Stuck-On-Drain for all my free tips, tricks, and the top main drain clips so your current robot doesn’t get stuck.

Waterline Cleaning

The waterline is where most robots give up — they climb, stall, and slide back down. In my testing, the Sigma climbs like it’s on rails and actually scrubs at the waterline, where sunscreen and body oils build that gray ring. Strong suction holds it to the wall while the upgraded brush does the contact work, so it’s not just touching the tile line — it’s working it.

Smart Navigation — Now With a Gyroscope

Most robots look like they’re bumping around at random. The Sigma moves with a plan, and the gyroscope makes that plan visibly straighter — clean parallel lanes, quicker recoveries off obstacles, and no wasted laps over floor it already covered. It squares itself out of corners instead of grinding in them, and it works around drains, ladders, and steps without getting hung up. It is, and I’m not ashamed to admit this, weirdly satisfying to watch.

The MyDolphin Plus App

Unlike the Premier, the Sigma comes with a full smartphone app — and in my testing, it actually works. That’s not a given in this category. More than one cordless robot I’ve reviewed dropped its app connection the moment it went underwater. The MyDolphin Plus app held its link the entire cycle, and it let me set weekly schedules, pick cleaning modes, steer the robot to a trouble spot, and check progress without walking outside. That’s what a pool robot app should be.

“But What About the Cord?”

I hear you, and I watched for it. The Sigma’s cable has an anti-tangle swivel, and across weeks of daily cycles, I haven’t untangled it once. The swivel lets the robot spin and change direction without twisting the cable into knots. It’s a problem solved with engineering instead of solved by deleting the cord — and my PSI chart shows exactly what deleting the cord costs you in suction.

The Time Math

Time is the whole reason to buy a robot, so here’s mine. Manual vacuuming and brushing ran me one to two hours a week. A cordless robot needs about ten minutes of handling every day — call it 70 minutes a week. The Sigma needs about ten minutes once a week. By my math, that’s an hour or more back every week, and north of 40 hours a year, just from not babysitting pool equipment.

What’s the Downside?

No product is perfect, so let’s be straight about the knocks on the Sigma. First: the price. With a retail price of around $3,000, this is the top of Dolphin’s ProLine and it shows. Now, you can usually find the Sigma on sale for well under $3,000, but at this premium price tier, it is frustrating that the new Active Center Brush is an extra paid add-on. When you’re paying top dollar for the best of the best, you expect all the performance parts to be in the box.

My take after running it next to the cheaper alternatives: you’re paying for the parts you can’t see — three motors, real filtration, and true automation — and in my experience, those are exactly the parts that decide whether your pool stays clean. Stretch the cost over five years of ownership, factor in the hours you’re not spending on maintenance, and the work the filtration takes off your main system. In my opinion, the gap between the Sigma and a cheaper robot you might replace along the way shrinks fast.

Where the Sigma Fits in Dolphin’s Lineup

Quick lineup context, because I get asked this constantly. The Premier is the raw-suction king of my logbook at 2.2 PSI, with the swappable MultiMedia filtration — but no app. The Sigma gives up two-tenths of a PSI and trades them for the app, gyroscope navigation, and the top-load NanoFilters. The Quantum Pro sits just below at 1.9, and the Cayman at 1.5, for smaller budgets.

And from other brands, the new Clear UV posted 2.09 PSI on my gauge and layers UV sanitation on top.

Is the Dolphin Sigma Worth It?

Bottom line: the Sigma isn’t hype. Out of everything I’ve tested, only two robots have out-pulled it on the manometer. With the app, the polish, the filters, and the overall build quality – it truly is the top of Dolphin’s lineup.

Nothing cordless has come close to matching its combination of suction, intake width, filtration, and set-it-and-forget-it automation. If you’re tired of vacuuming, brushing, and babysitting chargers, this is the robot I’d point you to. It’s the one I keep choosing to leave in my own pool — and around here, that’s the highest praise there is.

You’ll find the best deals I can find on the deals page. Got a robot you want on the manometer next? Tell me in the comments. Thanks for watching — I’ll catch you on the next one!