Zip Your Media In, Keep Spills Out Tie-string media bags loosen, gape open, and dump loose media all over your filter chamber. Fumbling with knots while you fill them is the last thing you want mid-maintenance. The Seachem Zip Bag features a corrosion-proof plastic zipper and durable seams to neatly and securely contain filter media in your specific filter setup. With no strings or ties to complicate filling and placement, it stays shut with no spills. Choose from two sizes and mesh types to match your exact media. The Zip Bag comes from Seachem Laboratories, the chemistry-driven company founded in 1979 in Madison, Georgia, and is designed to pair with Seachem's range of filter media. That attention to practical detail is why it uses a corrosion-proof plastic zipper and durable seams, so it holds up in constant contact with aquarium water where flimsier bags loosen or corrode. Pick the size and mesh that fits your media, fine for most media or large for biological media. Fill the bag and close the corrosion-proof plastic zipper. Place it in your filter so water flows through the contained media. Fill it, zip it, forget it. Add to cart. What It DoesThe Seachem Zip Bag contains aquarium filter media in a stay-shut, no-spill bag using a corrosion-proof plastic zipper and durable seams. It has no strings or ties to complicate filling and placement, and comes in two sizes and mesh types to accommodate your exact needs. Available SizesSmall (fine mesh, best for most filter media): 12.5" x 5.5", holds 1 liter. Large (large mesh, best for biological media): 19" x 17", holds 18 liters. Why Seachem Zip Bag No-spill closure: a corrosion-proof plastic zipper keeps the bag stay-shut, so loose media does not escape into your filter chamber. No strings or ties: without knots to fumble, filling and placement are fast and simple, even mid-maintenance. Two sizes and mesh types: a fine-mesh small bag suits most filter media, while a large-mesh large bag suits biological media, so you can match your exact setup. Durable and corrosion-proof: durable seams and a corrosion-proof zipper stand up to constant submersion for long-lasting reuse. Best ForFreshwater and marine aquarists who want a secure, easy-to-fill bag for chemical or biological filter media. The small fine-mesh size fits most media, while the large mesh size suits bulk biological media in canisters, sumps, and media chambers. FAQ Which size should I choose? The small fine-mesh bag (12.5" x 5.5", holds 1 liter) is best for most filter media, while the large mesh bag (19" x 17", holds 18 liters) is best for biological media. Where does it go in my filter? Fill it, close the corrosion-proof zipper, and place it in your filter so water flows through the contained media. Freshwater or marine? Both. The Zip Bag contains filter media for freshwater and marine systems alike.