Review on CerMedia MarinePure Biofilter Media Gems - 90g, Tan (905002) by Crystal Keenan

You'll need to wash them well to remove as much sediment as possible, but these miracles work wonders for keeping bacteria alive in your tank . I took a garbage sponge from a 5 gallon aquarium and replaced it with a small ziplock bag and then filled the aquarium with bacteria. After a month of really unstable water things have settled down and we now only change the water twice a month. Stop reading and buy them now. You will not be disappointed.