ECOVACS Ultramarine P1

The cleaner is rated by its maker for in-ground pools, which are deeper, have steeper walls and usually a real deep end.

In-ground use is what demands wall climbing, waterline scrubbing and enough battery to cover a large surface in one cycle.

The cleaner is rated for above-ground pools, which have soft liners, a flat floor and low walls.

Not every in-ground robot is safe on a vinyl above-ground liner, and many above-ground models clean only the floor, since there is little wall to climb. A cleaner rated for both is the safer buy if you may change pools.

The largest pool surface the manufacturer rates the cleaner for in a single cycle, in square feet.

A 16 x 32 ft rectangular pool is about 512 sq ft of surface, so most residential pools sit well under 1,000 sq ft. Makers of cordless models quote generous figures measured in the easiest mode, so a rating of roughly twice your pool area leaves margin for walls and waterline.

On corded cleaners the real limit is the cable, not this number: check the cable length against the longest distance from the outlet to the far end of the pool.

The cleaner vacuums the pool floor, which is where sand, grit and sunken leaves settle.

Every submersible robot does this. Surface skimmers do not: they float and collect only what is still on top of the water, so they answer NO here.

The cleaner climbs and scrubs the pool walls instead of staying on the floor.

Walls are where algae takes hold, so wall climbing is the single biggest step up from an entry-level floor-only model. Climbing needs enough suction to hold the robot against a vertical surface, which is why the cheapest cordless units skip it.

The cleaner works the waterline, the band at water level where sunscreen, body oils and pollen leave a greasy tide line.

This is the job people hate doing by hand, and it is what separates a mid-range robot from a premium one. It is harder than wall climbing: the machine has to hold itself at a constant depth and scrub horizontally instead of driving straight up.

The cleaner collects floating debris from the surface, before leaves and pollen sink and stain the floor.

Two very different machines answer YES here: dedicated solar skimmers that float and run all day, and premium submersible robots that spend part of their cycle at the surface. Removing debris while it still floats is the cheapest way to keep a pool clean, because anything that sinks has to be scrubbed later.

The cleaner handles steps, benches and tanning ledges instead of driving past them.

Steps are the hardest part of a pool for a robot: it has to detect the change of height, climb it and stay on a surface that may be only 20 cm under water. Makers state the step height and the minimum water depth they support, and most cordless models simply skip these areas.

How much water the pump moves, in gallons per hour (GPH), as published by the manufacturer.

Higher flow picks up heavier debris such as acorns and wet leaves, and it is also what holds the robot against a wall. Figures run from about 2,000 GPH on entry-level above-ground units to more than 8,000 GPH on flagships.

Treat it as a rough class indicator, not a measured result: makers quote it in the most favourable mode and with a clean filter, and a full basket cuts it sharply.

The number and type of brushes the cleaner scrubs with, as the maker describes them (single roller, dual roller, quad roller, PVC or rubber).

Suction alone lifts loose debris; brushes are what remove what has stuck to the surface. Dual and quad roller systems also help the robot climb, and rubber or PVC combinations are chosen for how they grip a specific pool surface.

How many cleaning programs the cleaner offers, counting the modes the maker lists (floor only, walls only, waterline, full pool, eco, turbo, surface).

More modes means finer control over where the battery goes: a quick floor-only pass before a party costs a fraction of a full cycle. On corded models the equivalent is a smart cycle that decides the duration itself.

The cleaner is designed to follow the wall closely and work the floor-to-wall corner, instead of turning early and leaving a dirty band.

Corners and the cove where the floor meets the wall are where debris collects, and they are the first thing owners check. Makers implement it with side brushes, a squared chassis or wall-following sensors that hold a fixed distance.

How the cleaner decides where to go: random bouncing, gyroscope path planning, ultrasonic sonar, AI camera vision, or a combination of them.

This is the spec that decides whether a cycle covers the whole pool or leaves patches behind. Random models eventually cover a small pool by luck and waste battery doing it; mapped models drive in lanes and finish sooner, which matters most on a cordless robot with a fixed charge.

The cleaner carries a camera and identifies what it sees, so it can drive towards dirt and around obstacles.

Vision is what makes a robot spend its battery where the debris actually is, instead of covering the pool evenly. It is the newest of these technologies and appears mostly on premium 2025 and 2026 models.

The cleaner uses ultrasonic or time-of-flight sensors to measure the pool and build a map of its shape.

Sonar works where a camera struggles: cloudy water, night cycles and shaded pools. A mapped pool is what makes zone cleaning and a predictable finishing point possible.

The cleaner detects drains, ladders, lights and pool toys and drives around them instead of getting stuck.

Getting wedged under a ladder ends a cycle silently and leaves the pool half done, so avoidance is worth more than raw suction on a pool with obstacles.

When the cycle ends or the battery runs low, the cleaner drives itself to the waterline at the edge of the pool so you can reach it.

Without this, a dead robot sits at the deep end and has to be fished out with a pole. It is the single feature that most changes how a cordless cleaner feels to live with.

The cleaner returns to a dock and recharges on its own, without being lifted out of the water.

This is the newest step in the category, implemented with floating charging docks and, in 2026, with robot arms that lift the unit out of the water. It removes the last manual chore, but the dock takes up space at the pool edge and adds a lot to the price.

How much debris the basket or bag holds, as published by the maker (in liters or gallons).

Capacity decides how often you empty it, which in practice decides whether the pool gets cleaned. A small basket fills up mid-cycle in autumn and the robot keeps driving with no suction left.

The size of the smallest particle the filter traps, in microns. A lower number is finer.

Coarse filters around 180 microns catch leaves and insects; fine filters between 3 and 50 microns also catch pollen, algae and the fine silt that makes water look dull. Fine media clogs faster, which is why most makers ship two sets and expect you to swap them by season.

The cleaner filters through two media at once, a coarse layer for leaves and a fine layer for silt.

A single fine filter clogs quickly and a single coarse one lets the fine dirt straight back into the pool. Two layers keep suction up for a whole cycle without losing the small particles.

The basket is emptied from the top of the cleaner, without turning it upside down.

The alternative is flipping a dripping robot over on the deck to open a bottom hatch. Top access is what lets you empty it in seconds with the unit still on the coping.

The cleaner warns you when the basket is full, through an indicator on the unit or a notification in the app.

A full basket makes the robot lose most of its suction while it keeps running its cycle normally, so nothing on the surface says the pool is not being cleaned. This is the only feature that catches it.

The cleaner runs on a rechargeable battery, with no floating cable and no power supply at the pool edge.

Cordless removes the tangled cable and the transformer, and it is the only option when there is no outlet near the pool. The trade-off is runtime: a battery cycle ends when the charge does, while a corded model can keep going and usually moves more water for the same money.

The length of the floating cable on corded models, from the power supply to the cleaner.

The cable, not the pump, is what limits a corded robot: it has to reach from the outlet to the farthest corner of the pool with slack to spare. Cordless models answer "-" here.

A tangle-reducing swivel matters as much as the length, since a twisted cable stops the robot short of the far end.

The size of the battery pack, usually given in milliamp-hours (mAh) or watt-hours (Wh).

Capacity alone does not decide runtime, because motor count and suction differ between models, but within a brand a larger pack means a longer cycle. Corded models answer "-".

How long the cleaner runs on a single charge, in the mode the maker quotes.

Runtimes between 90 and 300 minutes are typical, but the number depends heavily on the mode: floor-only lasts around twice as long as floor plus walls plus waterline, and surface skimming lasts longest of all. Compare the figure for the job you actually want done.

Corded cleaners answer "-": they run as long as the cycle lasts.

How long the battery takes to charge fully.

Most cordless pool robots need between three and five hours, which is longer than they run. That is what makes them a once-a-day machine and why runtime matters more here than on a robot vacuum that can top up between rooms.

The cleaner comes with a dock or stand it charges on, instead of a bare barrel connector on the unit.

Docks matter more than they sound: a wireless or magnetic contact dock has no exposed pins to corrode in a wet, chlorinated environment, and it gives the robot somewhere to live between cycles.

The cleaner carries solar panels and recharges itself from the sun while it works.

This is what allows a surface skimmer to run all day, every day, with nothing plugged in: it collects floating debris before it sinks, which is when it is easiest to remove. Output drops on cloudy days and the panels need rinsing, so most solar models also accept a cable charge.

The cleaner connects to your home Wi-Fi network on the 2.4 GHz band, which reaches further and through more obstacles than 5 GHz.

Water blocks Wi-Fi almost completely, so a submerged robot cannot hold the connection: makers use it while the unit is at the surface or docked, to schedule cycles, push firmware and report status. Some models add a floating buoy or a gateway to keep the link alive during a cycle.

The cleaner pairs directly with your phone over Bluetooth, without going through the home network.

Bluetooth is the fallback most pool robots rely on, because it works at the pool edge where there may be no Wi-Fi coverage. It only reaches the unit while it is at the surface, so it is used to start, stop and configure a cycle rather than to follow it live.

Additional connectivity options not covered by the standard protocols.

In this category that usually means an underwater link: LiFi, which sends commands as light through the water so a handheld remote keeps working while the robot is submerged, or a floating gateway that relays the app connection to the unit.

Google Home serves as a central hub for a variety of smart devices, including lights, thermostats, cameras, and speakers. It leverages Google Assistant for voice control, enabling users to manage their smart home with simple commands.

Amazon Alexa is one of the most widely used smart home systems, known for its compatibility with a vast array of devices. Users can control everything from smart lights to appliances using voice commands through Echo devices.

Apple HomeKit is designed for users in the Apple ecosystem, providing a seamless way to control compatible smart devices through iOS devices using the Home app or Siri. It emphasizes security and user privacy.

SmartThings is a flexible platform that connects a wide range of devices from different brands, offering a unified interface for control. It supports various communication protocols, allowing for extensive device compatibility.

Home Assistant is an open-source platform that allows for extensive customization and integration of a wide variety of smart devices. It supports a multitude of protocols and brands, making it ideal for tech-savvy users.

Matter is a unified, open-source connectivity protocol designed to standardize and simplify communication between smart home devices from different manufacturers. Developed by the Connectivity Standards Alliance (formerly the Zigbee Alliance), Matter aims to improve interoperability, security, and reliability across various smart home ecosystems.

Matter operates over existing networking technologies, including Ethernet, Wi-Fi, and Thread, providing flexibility in device connectivity. Its IP-based nature allows seamless integration with existing internet infrastructure and cloud services.

The cleaner is controlled from a phone app, not only from a button on the unit.

The app is where modes, schedules and cleaning reports live. Entry-level and many corded models have no app at all: you press a button and the cycle runs with whatever settings it shipped with.

The cleaner can be set to run on given days and times on its own.

A pool needs cleaning on a rhythm, not on impulse, so scheduling is what turns the robot into maintenance instead of a chore. On cordless models the schedule has to fit around charging, which is why self-docking and scheduling usually appear together.

The cleaner can be steered by hand, with a physical remote or from the app.

This is how you send the robot to a specific spot after a storm, and how you drive it to the edge to lift it out. Under water, remotes work over LiFi rather than radio, because Wi-Fi and Bluetooth do not travel through water.

The ability to create automated actions based on sensor readings or schedules.

Automations can trigger other smart devices, send notifications, or adjust settings without manual intervention.

The ability to track and store historical data over time.

For a pool robot this is the cleaning log: which cycles ran, how long they took and how much of the pool was covered. It is also the first place to look when the water stops looking clean.