Change your robot vac's main brush when it looks worn, not by the calendar.

Roughly every six to twelve months is a decent rule of thumb, but the real answer is: replace it when you can see it’s degraded.

The brush is the part that actually touches the floor day after day. Bristles bend, rubber fins crack, and pet hair gets baked into the axle. You’ll notice it first as poorer pick-up on edges, or the vacuum suddenly sounding like it’s fighting a losing battle.

Check your brush every month during filter cleaning. If bristles are missing, the rubber is gouged, or the bearings are tight, swap it. For heavy pet homes or thick carpets, expect closer to six months. For a robot that barely runs, you might stretch it to a year or more.

Manufacturers want you to buy parts on schedule.