Lightweight and very porous biomedia for benedicial bacteria. Economical, versatile and easy to use. Inert and can be used for all types of aquarium systems. The classic biomedia of TGR. Can be placed in media bags or baskets, canister filters, hang-on-back filters or overhead/trickle filters. Best used with TGR Reduce for nutrient management in reef aquariums. Muriatic acid washed.Recommended usage: Place enough pumice in a media bag or preferably a reactor with slow flow rate. Rinse with old tank water periodically to remove detritus. Ideal quantity 1 pack for 30 to 75 gallon tank.