Cleaning Your Filter

Understanding Your Filter

Your filter does three things: mechanical filtration (traps debris), biological filtration (houses beneficial bacteria), and sometimes chemical filtration (activated carbon). The biological filtration is critical — billions of bacteria process waste.

When to Clean

Clean when you notice reduced flow, debris buildup, or a clogged intake. For most filters, every 2-4 weeks. Over-cleaning is worse than under-cleaning.

How to Clean

Hang-on-Back (HOB) Filter

1. Turn off the filter.
2. Remove media. Rinse in old tank water — gently squeeze the sponge.
3. Clean the impeller (check for hair/debris).
4. Rinse the housing with tap water (no bacteria there).
5. Reassemble and restart.

Canister Filter

1. Unplug and disconnect hoses.
2. Remove media trays to a bucket of old tank water.
3. Rinse each tray. Clean at most 50% of biological media at a time.
4. Clean impeller and O-rings.
5. Reassemble — ensure O-rings are seated to prevent leaks.

Sponge Filter

Remove the sponge, squeeze in old tank water until clear, reattach. Very easy.

Critical Rules

• NEVER clean all media at once (clean at most 50%).
• NEVER use tap water to rinse biological media.
• NEVER replace all filter media at once — keep old alongside new.
• NEVER clean your filter and do a large water change on the same day.

Pro Tip: When replacing filter media, cut the old one in half and keep it in the tank for 2-3 weeks alongside the new one. Bacteria will migrate to the new media.