Filter PAK 4001, 4000, 8000 Replacement Filter Bags : FP-50-5
50 micron filter bags. Comes with 5 bags. Works with the 4000, 4001, and the 8000 filter paks.
We recommend 25 micron if using plastic media and a 15 micron if using ceramic media. All filtration systems come with a 15 micron if you'd like to use the same filter bag.
A 5 micron is the smallest hole size and lets less particles through. A 100 is the largest hole size and lets the most particles through.