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Filter Cartridge Replacement Instructions

After creating an enchanted underwater world for your pet fish you'll want to keep the water clean and healthy in your aquarium.

Top Fin® is one of the popular fish tank setups for beginners. So, how do you change the filter cartridge and how often should it be replaced?

Changing a Filter Step-by-step Instructions

To maintain clean aquarium water, you should be changing the Top Fin filter cartridge every two (2) to four (4) weeks - or sooner if it becomes clogged and obstructs the flow.

As a rule, there are 5 basic steps for filter replacement. You'll need:

A new "compatible" replacement filter cartridge (remember there are different size Top Fin refill cartridges available).
Access to a clean towel so you can catch any drips of water.
Optional: A small bucket of clean water to rinse the new cartridge.

Pro Tip: One of our troubleshooting sections contains Top Fin® heater instructions if you need some help to set up the water temperature.

Step 1: Turn Off the Power Outlet for the Filter

Always unplug the filter from the electricity supply before you start the procedures to avoid any electrical hazards.

It's best to wait a few minutes after isolating the power to let the water "settle" - especially if the filter you have is a hang on back (HOB) type.

Step 2: Removing a Dirty Cartridge

Element filters help to remove unwanted organic waste and heavy metals. But, you should remove the cartridges if you are medicating the water because the carbon may absorb some of the chemical treatments.

If you can see a "red" marker on the lid (instead of "blue") it means gunk has built up and pushed up the lever to let you know it's time to change the filter.

So, to change a Top Fin filter cartridge:

Remove the filter lid (if there is one) by pushing it up with both hands.
Carefully lift out all of the dirty cartridges. You may also see a blue plastic bio cartridge (for absorbing odours, pigments, and chlorine) that slides inside a separate slot.
Place the old cartridge in a plastic bag and dispose of it appropriately (e.g. in the garbage bin).

Pro Tip: The Top Fin Half Moon Aquarium starter kit contains a single LED light, a black plastic hood with feeding door, and a Top Fin "Element" filter with two (2) separate cartridges.

Step 3: Installing a New Cartridge

Briefly rinse the new filter cartridge under the cold water tap (or in a bucket of dechlorinated water) to remove any carbon dust or residue.

Next, gently slide the new cartridge into the designated filter slot. The blue (mesh) side should be facing the water flow side at the back. Water will not flow smoothly unless it is seated properly.

This part is important:

You need to pour water into the filter box (e.g. with a small jug) and it is better to use aquarium water (e.g. not tap water). Push the lid back on and it should be secure when you hear a "click" sound.

Pro Tip: Remember the "intake tube" goes inside the aquarium and the plastic box sits on the outside - usually hanging on the back of the tank.

Step 4: Restarting the Filter

Plug in the filter and check that it is running properly. You can prime it by adding some tank water into the filter chamber before you power up the unit.

Step 5. Checking the Filter Flow

In most cases, the filter starts working as soon as you plug in the power and water should start to flow through it. You may need to clean the impeller if the flow is weak.

Remember to monitor the quality of the water for at least a few days. Even though filter cartridges need replacing every 2 to 4 weeks, try to avoid changing all of the filter media at the same time to retain some of the beneficial bacteria.

Pro Tip: After switching it on, it's normal for the filter to make some noise until the water has circulated through the system. You can also turn the switch on top of the filter lid to adjust the water flow rate.