These pool cleaners have scrubbing brushes which they use to dislodge dirt from pool floors and walls, however, they will not effectively loosen algae from pool surfaces but will effectively pick up already loosened ones. If your pool has a severe algae problem, this can make the pool surfaces slippery and prevent these pool robots from getting a firm grip on the surfaces, prevent them from climbing as well as they should, and generally interfere with their cleaning performance. Shock chlorination treatment should be used to treat algae and ensure the robots are not in the pool during such treatment.