Tetra ReptoFilter 10i and 3-Pack of ReptoFilter Filter Cartridge Refills Tetra ReptoFilter 10i and a Bonus 3-Pack of ReptoFilter Filter Cartridge Refills Provides quality three-stage filtration, removing debris, discoloration, and odors and ammonia from terrariums with up to 20 gallons of water It's a mechanical filter - The ReptoFilter cartridge uses dense, dual-sided mesh to catch debris and waste It's a chemical filter - Ultra-activated carbon removes odors and discoloration It's a biological filter - Bio-Foam cultivates aerobic bacteria, which eliminate toxic ammonia and nitrites