Algae and Robot Cleaning: What a Robot Does and Doesn't Do

A robot can scrub algae off a surface. It doesn't treat the water that's growing it. Those are two jobs, and the robot does only the first.

What the makers describe

Maytronics says rotating brushes dislodge algae, dirt, chlorine-resistant bacterial biofilm and fine debris from pool floors, walls and the waterline¹. It's careful about reach, though. Most robots clean the floor, while some can also scrub algae from the walls and clean the waterline¹.

So the answer depends on the model. A floor-only robot won't touch algae on a wall. Check your manual for which surfaces yours covers.

The same page says suction and pressure cleaners are largely floor-only tools that cannot scrub algae¹. That's a maker comparing its own type of product with others, so read it with that in mind. It also says wall-climbing ability varies from robot to robot¹. Two robots can behave quite differently on the same green wall.

Where the algae goes

Brushing loosens algae. Then it's in the water, and the robot's filter has to hold it. Maytronics says an ultra-fine cartridge holds small particles, algae among them¹. A coarse basket has larger openings, so it's less able to hold such small pieces. That's a reading of the mesh idea, not a test result, and I haven't any source that measures it.

The robot keeps what it catches inside itself. It's separate from the pool's main filter and pump, and it sends particles into its own filter².

What a robot doesn't do

A robot isn't a water treatment. None of the sources here says a robot clears an algae problem in the water by itself.

One health authority describes what an algal bloom looks like: if the pool starts to turn green, an algal bloom is developing³. Its advice is to consult a local swimming pool shop for the best practice to minimise the bloom³.

That advice is from an Australian state health department, written for pools after floods or storms. It's still a clear pointer. Water care goes to a pool shop or the maker of your pool's equipment, not to the robot's manual.

Using what you've read

• Check which surfaces your robot's manual says it cleans.
• Check which filter is fitted. A finer one holds more small pieces.
• Empty and rinse the filter after a run with algae in it, as your manual directs.
• Take a green pool to a pool shop.

Never mix pool chemicals, and follow each product's label. Fine particles are covered in a page on silt and dust. The general picture is in the overview.

A robot's brushes wear and its filter fills, so after an algae run, empty and rinse the filter before the next one.