Renewable up to about 2 yrs. Works simularily to carbon Effective in freshwater with no carbon usage. Rinse several times in fresh water. If for use with fresh water fish, soak in Reverse Osmosis or distilled water to make sure all of the salt is removed. Reuse as before.
White beads turn brown or yellow indicating exhaustion.
In any case, regenerate when exhausted or every 5 to 7 days until the aquarium is clear. Kent Marine Nitrate Sponge is a granular zeolitic medium which works by two methods. It slowly directly adsorbs small amounts of ammonia that are released by fish and natural processes, and it fosters anaerobic bacterial denitrification due to its physical porous structure. This denitrification slowly reduces nitrate levels in the aquarium. Deionization or reverse osmosis filtration of tap water nitrates will also help if your tap water contains significant levels of nitrates.