Measure the grids -
Measure the grid's length(not including the port pipe at the top), and it's width (straight across) to identify the square footage of your filter.
The pool industry’s standard curved grids
come in 5 different sizes 24, 36,48,60, and 72 square feet; their respective lengths are 12, 18, 24, 30, and 36 inches.
Most DE filters use a grid pack of 8, which includes seven full grids (11.5 inches) and one partial (9.5 inches.) If you are only replacing a few of these grids measure the width to be sure which style you need.
For older models like the Jacuzzi Earthworks
, which use non-curved grids, you will need to measure all grids, as the various model sizes used a combination of two or three grid sizes per model.