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Filtration & Media


December 13, 2018 | By Tom Sarac

If you stop and think about it, a filter is basically a vessel that houses the filter media and pumps water through it. Filter media is the actual heart of what goes on in a filter.

There are certain filter media that are typical for ongoing mechanical and biological filtration duties. However, when it comes to chemical media these are often more short-lived, and need to be changed more frequently to do their job effectively.

We’ve already covered what these three types of filter media do – watch the video at the bottom of this page for coverage on filter media and its functions. Understanding the functions makes it clear why some types, like chemical media, require more frequent replacement.

When considering specific symptoms, which can be undesirable in an aquarium, you can quickly address the part you don’t like (i.e. green water aka suspended algae) with filter media and related products, but the underlying problem or cause is the long-term and thus more important part to solve.

Below are 5 typical symptoms and recommended solutions:


This is basically suspended algae, and its causes are excessive light (especially daylight) and nutrients.

Solution: Using quick clear and some fine polyester filtration pads (Fluval units are pre-cut to fit the media baskets), you will trap and remove the unwanted, green water-clouding algae. After that, discard the pads and address the possible causes to prevent or diminish the reoccurrence.


Odour can be an issue in new or heavily-stocked aquariums, including tanks with large fish that have grown and are perhaps ready for a larger aquarium.

Solution: Simply re-fresh the carbon with a change, review what you are feeding and how much, and then consider if perhaps it’s time for a larger tank.


While this is expected in a tank with natural driftwood, the intensity of the brown water colouration is controllable.

Solution: Properly pre-soak aquarium-safe decorative natural wood for up to a week in a bucket, changing the water daily. Follow with regular water changes and carbon replacements.


Caused by the unexpected loss of a fish, overfeeding or other factors.

Solution: A quick water change, using water with the same pH or a little lower than the aquarium, along with a fresh charge of ammonia remover will normally take care of the issue. Adding some biological enhancer along with a review of the biological filter media in your filter are good ideas. Fish grow, and so if the tank becomes heavily-stocked it might call for more bio-media and even an additional filter in the future.


Despite regular maintenance on your part, you may notice a steady increase in unwanted algae growth on your aquarium surfaces.

Solution: Testing for phosphate in your tank and straight from the tap is a good place to start. Tap water is tested to make sure that it is not importing phosphate into the aquarium. Using phosphate remover will drop levels and keep things under control, but it will have to be replaced. Identify the causes, for example in the case of a marine tank, you may want to consider more frequent water changes with reverse osmosis (R/O) water. Reducing fish load, pre-rinsing frozen foods with tap water and using less dry foods that may be high in phosphate are also good places to start. Then, you should seriously consider keeping fish and invertebrates that consume algae as part of your strategy to keep the aquarium clean.

The important takeaway here is to understand the difference between a symptom and a problem. By all means, clear the symptoms but address the problem too, otherwise you will be working to catch up all the time instead of preventing the issues in the first place with proper tank management practices.


Learn how Fluval filter media can help solve common aquarium water problems such as green water, ammonia spikes and unpleasant odours.


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