Bulk discount (12 sponges)

The active carbon sponge cleans the water of all chemical impurities by absorbing them in its active carbon. Consequently, these chemical impurities will not effect the bacteria - cultures inside the blue sponges. If the carbon sponge is left in the filter too long, it can release the chemicals back into the water. Consequently, we recommend you replace the carbon sponge every 4 weeks.