Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
PetSmart stores sell 2 sizes of fairly fine mesh bags for about $1 each, but you need to double them up to insure the particles don't escape into your tank.
I've also had good experience using organza material bags bought at gift shops or dollar stores/specialty discount stores. (They're used to package mainly wedding & birthday gifts). But you do need to replace them every 6 to 8 months or so, as the organza eventually deteriorates from the constant bleach re-charging. And keep in mind I re-charge my Purigen every 3 weeks, so the organza does last quite a while - about 10 bleachings.