Rinse before using. Insert the black sponge in the water inlet of the filter, to hold larger particles. Insert the blue sponge in the intermediate stage of the filter. Both sponges must adhere the filter walls. Water must go through the sponges. Rinse the sponges every 3 months using only tap water and replace them every 12 months. We advise washing one sponge at a time, waiting 7 days before washing the other one, to avoid destroying the bacterial fauna.