Maytronics Spring Cartridge Filter Panels, 4 Pack, 9991408-R4

The Maytronics 9991408-R4 is a four pack of spring cartridge filter panels for Dolphin robotic pool cleaners. It also fits the Pentair Prowler 820 and 830, which share the cassette design.

When to change them

Filter panels are the part of a robotic cleaner that actually holds the dirt, and they wear from the constant loading and rinsing. Once a panel tears at a corner or stops rinsing clean, the cleaner still runs its pattern but returns less to the basket and more to the water. Changing the whole set at once keeps the flow through the cassette even.

Sizing

Each panel measures 10-15/16 inches by 5-1/4 inches by 1/2 inch thick, excluding the extension tabs. Compare those figures against the panels you are removing if your cleaner is not on the fitment list.

One thing to check

The source information for this set is inconsistent about filter grade: one description calls it a coarse filter set, another calls it an ultra fine filter four pack. Both readings are carried in the specifications above rather than picking one. Match against the panels currently in your cleaner if the grade matters to you.