XINYOU XY-1831 FILTER Sponge  is able to be used in marine, fresh water, and planted tanks, which you are able to cut to the size you want which suits your filter. The experts according to the experiment conclude that the molecule’s hole size and softness are best suitable to develop the best for bacteria. The bio sponge is able to dissolve the waste of fish and also improve water quality and reduce the death rate of fish in tanks. Washing of bio sponge filter by using running tap water to clean, after washing and cleaning its shape will remain, the hole will not be blocked by dirty particulars, and it can be reused continuously.