This product is the only terrarium filter you'll need. 3 filters in 1. The ReptoFilter adjusts easily to high or low water levels with mounting suction cups. 1. It's a mechanical filter: The ReptoFilter cartridge uses dense, dual-sided mesh to catch debris and waste. 2. It's a chemical filter: Ultra-activated carbon removes odors and discoloration. 3. It's a biological filterL: Bio-Foam cultivates aerobic bacteria, which eliminate toxic ammonia and nitrites before water cascades back into terrarium. Unique design incorporates three stages of filtration for optimum performance. Uses easily replaceable ReptoFilter cartridges. The ReptoFilter fully assembled cartridges are tough on debris. .and easy on you.