Help to keep your aquarium sparkling with the Bacto-Surge high-density foam filter from Hikari. Made from light and airy sponge, this unique filter offers biological filtration, breaks down organic waste, and may even help to support better water flow. It's designed to be used in both freshwater and saltwater tanks—so aquarists of all kinds can benefit from this simple, straightforward solution! Use it for nano tanks, breeding or fry-holding tanks, quarantine tanks and with tanks that include slower-moving fish, such as the Discus.