om of the pool initially, steadily learning the layout of its cleaning job. With a line of drains that jut out considerably, we thought it might struggle to crawl over them or need to reroute. Instead, the M500 propelled over the surfaces with the brushes spinning, actually cleaning the surfaces of the drains.

Our test pool has a unique underwater layout with slopes, abrupt right angles, and even a shallow underwater ledge. The M500 launched up the slopes of the deep end smoothly. When it approached the areas of the pool where the gunite surface formed a right angle, it easily propped itself back on the rear curve of its treads and thrust upward without missing a beat.

The small underwater ledge was an interesting challenge for the M500, as it rose from the bottom of the pool by about six inches and jutted out from the side of the pool by another six inches. Honestly, we thought the robot would struggle with this since it was such a compact space. However, the M500 actually propped itself up the small ledge, scooted over, and then descended again. It actively scrubbed and cleaned a narrow, awkward space far better than any other robotic pool cleaner had before.

Waterline cleaning is often touted as a feature of modern robotic pool cleaners, but not all of them deliver. The M500, however, had remarkable dexterity when it came to climbing the walls of the pool and reaching the waterline. It made it to the surface of the water on every vertical pass-through, and it did an amusing little shimmy at the top to scrub and relocate itself a few inches over before descending again. This is also where the powerful grips on the tracks earn a nod of approval, as the slippery tile of this particular waterline make it hard for most robotic pool cleaners to maintain a grasp of the surface.

Visible Cleaning
The pool we used to test the M500 had enough visible debris for us to get a sense of its cleaning power from the get-go.

The M500 roamed the bottom of the pool and made leaves, a few twigs, dead bugs, and a definite shade of dinginess disappear. It obviously improved the clarity of the pool’s water within an hour of cleaning.

One particular area on a slope in the middle of the pool is prone to algae growth, which is visible from the surface if the pool hasn’t been cleaned in a few days. The M500 was actually able to scrub the grayish-black algae from the surface, leaving behind a clean streak we weren’t expecting. Aside from the M500’s obvious suction power, we have to applaud its active scrubbing power. The triple brush action and durable plastic bristles clearly did work on some stuck-on grime that most robotic pool cleaners, and especially traditional pressure side cleaners, wouldn’t have been able to conquer.

Invisible Cleaning (AKA, What’s in the Filter?)
The sign of a truly great robotic pool cleaner is when you open the filter cartridge after a cleaning job and you’re utterly grossed out. Spoiler: we were grossed out.

The springtime weather brought a lot of windy days, which blows a lot of silt and topsoil into in-ground pools. While we could tell the water’s clarity was lacking before the cleaning job and the bottom of the pool was a little dingy, we didn’t realize just how much dirt had accumulated in the water.

When we opened the filter cartridge, it was full of the larger debris we saw it suck up from the bottom of the pool. More impressively, it had a pretty thick layer of sludge at the bottom of the cartridge. The M500 had scrubbed and suctioned enough dirt and grime from the windy weather to make mud in the filter. It was gross, but it was satisfying to know that nastiness wasn’t in the pool anymore.

We used the standard fine filter for our maiden voyage with the M500, and we have to say it performed admirably. The filter lining itself was notably darkened from filtrating all of the smaller particles of grime from the water and the pool’s surface.

Customizability
One of the M500’s standout features for us is its customizability. The lower-end models in the M Series have one option for the cleaning cycle time and cleaning mode. However, the M500 has quite a few options.

There are three cleaning cycle times to choose from: 1.5 hours, 2.5 hours, or 3.5 hours. There are also four different cleaning programs: a standard cleaning that does an overall clean, a quick clean for floors and walls, a floor-focused clean, and a wall-focused clean. Add in the option to choose from three different filter types (ultra-fine, fine, and coarse), you can pinpoint a cleaning to cater to your pool’s specific needs on any given day.

Our initial cleaning was a standard 2.5 hour cleaning job with a fine filter. Like we’ve already described, the M500 performed remarkably well. But to get a feel for what else it could do, we replaced the filter cartridges with the ultra-fine filters and set the M 500 to do a quick (1.5 hour) wall-focused cleaning.

The M500 really did focus on the walls of the pool, staying vertical about 90% of the time. After the 1.5 hour job was completed, we checked the filters and were impressed with what all the ultra-fine consistency was able to capture. Even though the initial cleaning was successful, the wall-focused cleaning with an ultra-fine filter must have scrubbed a little deeper and removed even more particles from the pool’s vertical surfaces.

Customizability also spans to scheduling and control, too. From the multi-function power supply you can schedule cleanings, set a weekly timer, or start a cleaning job on the fly. The M500 is also compatible with the MyDolphin app. Using this app on your smartphone, you can easily schedule cleanings and begin jobs from an easier user interface. The app also has a manual navigation tool. From here you can “drive” the M500 to specific spots of the pool for any spot-cleaning needs.

Maintenance
The M500 doesn’t require much of you at all. The most attention it needs is in cleaning the filters, but even that is far easier than most robotic pool cleaners we have come across. Dual top-loading filter cartridges pull out of the M500 easily, and they unlock to release any larger debris from inside the cavity. All that’s left is to rinse the filters clean, then reinsert them. But be sure you don’t let a dirty filter dry out – the dirt and grim only washes out when wet.

Plus, the M500 comes with a matching caddy with your purchase. Since the robot weighs 24 pounds, the caddy makes life a lot easier when it comes to transporting and storing it.

How the M500 Measures Up
The Dolphin M500 robotic pool cleaner meets or exceeds all of our expectations.

Many higher end pool cleaners that tout modern features and smart technology are often bogged down by the extra bells and whistles, and their performance suffers. But the Dolphin M500 has struck a fine balance between features and performance. Its powerful motors and complementing navigation software ensure complete coverage, and it can propel itself in every direction. The real kicker is how much the M500 is able to pick up, thanks to its scrubbing brushes and filtration system. More than just cleaning the pool, we will go so far as to say it actually took a step toward purifying it. That coupled with its energy efficiency and easy maintenance makes it a robotic pool cleaner that goes above and beyond our expectations.

As the top of the M Series line, it is certainly an investment. But it simplifies pool maintenance and lowers the cost of running your pool in the long run. If you ask us, the Dolphin M500 is a class act you won’t regret buying