Activated carbon is a popular and effective filter media for keeping aquarium water clear and odour-free. But should you leave it in the bag when using it in your filter? The short answer is yes—with one important detail.

Keep It in the Mesh Bag (Not the Plastic Packaging)

Activated carbon works best when placed in the mesh bag provided, but you must remove any plastic outer packaging first. Carbon is made up of small, highly absorbent particles, and if left loose, these pieces can escape into your aquarium, clouding the water and causing issues.

Why Carbon Works Better Clumped Together

When kept in the mesh bag, the carbon pieces remain clumped together, which increases the contact between water and carbon. This maximises its ability to absorb odours, discolouration, excess nutrients, and even traces of medication.

How Often Should Carbon Be Changed?

Activated carbon is like a cup—it absorbs impurities until it reaches capacity. Once full, it can release those trapped elements back into your aquarium, which can harm water quality. To avoid this, replace carbon every 2-3 months , depending on your tank size, stocking levels, and why you’re using it.

A well-maintained aquarium is always healthier and more beautiful, so frequent carbon changes are essential.