Fully submersible (internal) filters are perfect if you have an area in your aquarium where water flow needs to be increased. They are effective if your tank carries a high bioload and is in need of supplemental filtering. Low-water habitats, such as paludariums, are also ideal spaces for an internal filter. The general rule of thumb is to use an internal aquarium filter on small tanks under 20 gallons. Once you know that you need one of these filters, how can you find the best internal aquarium filter?
How Internal Aquarium Filters Work
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This small but powerful filter allows for a choice of filter media. It also rarely clogs and is very affordable. Like all internal filters, the primary downside is that cleaning is cumbersome because it must be removed from the aquarium. Being able to choose different media is a perk because you can use different brands, or choose less-expensive filters.