The best filter is the one that matches what is actually in your pool. Modern robots let you swap media, so use the right one for the job.
Coarse Media and Leaf Bags
For heavy loads of leaves, acorns, pine needles, and twigs — especially in fall or after a storm — use a coarse cartridge or an oversized leaf bag. These hold a large volume without clogging so the robot can keep working through a big mess. More on this in do pool robots pick up leaves.
Standard Cartridges
For routine, everyday dirt and medium debris, the standard cartridge that came with your robot is usually fine. Just keep it rinsed after every cycle so it does not clog and cost you suction.
Fine Media and NanoFilters
When you are fighting silt, sand, pollen, algae, or cloudy water, you need fine filtration. NanoFilters use pleated microfiber to capture microscopic particles that standard filters push right back into the pool. They are the upgrade we recommend most — see do I need NanoFilters to decide. They handle sand and algae far better than coarse media.
Where to Get Them
Match your media to the season and stock a spare so you are never stuck. Browse cartridges, leaf bags, and NanoFilters on our parts page. Robots like the Dolphin Sigma ship ready for NanoFiltration out of the box.
