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Aquarium Filter

Internal Aquarium Filters - Pros & Cons, And How To Use Them

Internal Aquarium Filters - Pros & Cons, And How To Use Them

Today, we will deal with how to use an internal aquarium filter and what Pros & Cons you can expect hereafter. Looking into aquascaping, one will hardly come across internal filters, as in the most artistic area of freshwater aquariums, first and foremost, one would like to have as little technology as possible placed within an aquarium. However, the aquarium hobby extends far beyond aquascaping. Internal filter units have been used in the hobby for a very long time, and they certainly serve their purpose. For these filters to do their job reliably and satisfactorily, certain things should be considered, especially regarding maintenance. Without further ado, let's get down to business.

Pros & Cons Of Internal Filters

In this first section, you will get a taste of whether such an internal filter would suit your liking or whether you are more the type for external filters or hang-on filters.

Sicce Shark Pro internal filter


  • The purchase price is the cheapest compared to other aquarium filters.
  • If there is little storage space around the aquarium, no problem because they will be placed inside the aquarium and have no space requirements outside.
  • Internal filters are straightforward to install to remove without any hassle. They are easy to install and easy to remove.
  • Some internal filters also offer an aeration option with an air inlet, which is why they are very popular among many aquarists in bringing oxygen into the aquarium.
  • The aquarium water remains in the aquarium for filtration and does not have to be transported out of the aquarium via hoses, as with external filters. Therefore, with internal filters, it is virtually impossible for water to leak out due to a defect or improper use.


  • Generally, internal filters have a low filter capacity. Therefore, the filtered water's purity is not as good as with external filters. As a rule, fewer filter materials fit into an internal filter than an external one.
  • When removing the filter chambers, for example, for cleaning purposes, previously filtered-out debris may be released.
  • Internal filters take up space inside the aquarium and, therefore, away from the creative area.
  • From an aesthetic point of view, an internal filter is also not the measure of all things. Even if you use decoration and aquarium plants to hide the filter behind it, making it "invisible" is almost impossible.
  • The cleaning can become annoying over time because you should clean the filter suds frequently. Ideally, weekly or bi-weekly so that the filter does not clog and can do its job well.

How To Use Internal Aquarium Filters

First, think about the best position for the internal filter in the aquarium so that it is hardly noticeable later on. Just because it is an internal filter doesn't mean it will be visible to the viewer. We recommend arranging the aquarium layout so that the view of the filter is obscured as much as possible by better-looking decorations and plants. Be sure to leave enough space around the filter to be easily accessible, and the filter inlet and outlet are not blocked. We recommend placing an internal filter and all other technical components at their final position in the aquarium before you set up the decoration and planting.

The next point is crucial and should be taken seriously, especially for the benefit of the livestock. And that is once-a-week maintenance to sustain good filter performance. This is because sponges clog easily; the finer a filter media, the faster this happens. A dirty, clogged filter will quickly lose performance, causing problems with water quality, algae, and in the worst case, livestock.

Like any other filter, an internal one should operate 24 hours a day. If a filter is inactive, the important filter bacteria are no longer supplied with sufficient oxygen due to the lack of water flow. The first bacteria die off after about 45 minutes of filter inactivity. This can consequently lead to severe problems with the livestock and even death.

OASE BioPlus internal filter

Upgrade Your Filter Media

Is your filter still loaded with the factory media? We recommend equipping a filter with other biological filter media, but this is usually not included with the purchase from the manufacturer.

You can add many different filter media, including Seacham Matrix and Purigen. With most filters, existing filter media can be replaced, in whole or in part, with higher-quality media.

Such high-quality filter media will significantly improve water quality and clarity in your aquarium. Depending on which filter media you use, this will also affect the filter flow. For example, a fine-pored sponge will create more resistance than a large-pored sponge, reducing water flow slightly.

If you would like to find out more about filter media, then take a look here.

Further Recommendations

  • Make sure the filter does not ripple the surface too much. Place the filter outlet a few inches below the water surface, and direct the flow to create only a slight ripple on the surface. This is sufficient to get enough oxygen into the aquarium without expelling too much CO2, which is essential for plant growth.
  • Sponges installed by the manufacturer sometimes serve to protect smaller fish species in addition to filtering. Ensure you do not lose such a protective function when replacing filter media. When keeping small shrimp species such as Neocaridina shrimp, an internal filter inlet should be additionally equipped with suction protection from the outside. Dwarf shrimp usually reproduce quite well; without adequate protection, the tiny baby shrimp can be sucked in by the filter, which is fatal. If you are interested in this topic, you can find more information here "Protect shrimp from filter & surface skimmer intake?"
  • The Sicce Shark Pro internal filter can easily be used horizontally. We use it in a shallow aquarium where we temporarily store plants from dismantled aquariums. Perfect!
  • The filter chamber(s) of the Oase Bio Plus internal filter is remarkably easy to remove and install thanks to the built-in magnetic mechanism that holds the filter chambers in place. Very practical and helpful, especially during maintenance work!
  • The suction cups that hold the filter to the aquarium glass are something most people struggle with at some point. The suction cups only work well on clean glass. So if your glass is covered in algae or other debris, you should clean it first with cleaning tools before installing your filter. It is good practice to replace the suction cups with new ones every 6-12 months, as adhesion can weaken after extensive underwater use. During weekly maintenance, check for any damage and replace damaged suction cups.

Do You Have Questions About Internal Filters?

Our customer service is at your disposal. We are also delighted to assist you with any other aquarium-related topics.

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