This is an approximately 6″ x 12″ x 2″ medium density Blue Foam Sponge Block.
These Foam Sponge Blocks are great for basic filtration or biofiltration. They can be used to fill a void left by other biological filtration.
When used with the Aquaripure in lightly and moderately stocked tanks, it is recommended you rinse them out in fresh tap water regularly to prevent a strong bacterial colony from forming on them. Their medium density will capture a lot of organics before they are converted into nitrates. In well stocked tanks they can provide additional biofiltration as well as being used as ordinary physical filtration.