Marina Slim – Review + Opinions

The Marina Slim Series range of cascade filters masters the art of not taking up too much space and at the same time providing great filtration, thanks to its large storage volume for filter media.

Join us in our analysis of the Slim range of cascade filters for aquariums from the Marina house, and you will discover everything that this filter for aquariums can offer you.

The waterfall filter, also known as a backpack filter or simply a hanging filter, has often been the easiest option for those looking for an easy-to-use external filter that doesn’t take up too much space.

The Slim Series from the Marina house is another of those well-known brands in the world of aquarism. This brand belongs to the Hagen group, which is already indicating that we are dealing with a quality product.

The Hagen house offers this wonderful Marina brand backpack filter in three sizes:

  • Marina S10 – up to 38 Liters
  • Marina S15 – up to 57 Liters
  • Marina S20 – up to 75 liters

The Marina Slim filter comes with all the necessary materials. It comes with filter cartridges that allow the device to work immediately.

In this review of the Marina Slim waterfall filter we are going to see all the features as well as the quality of this device.

Slim Series Marine Cascade Filter

The beautiful design of the Marina Filter Slim waterfall filter has been created by the same engineers who built the Aquaclear filters and is produced by the renowned Hagen company.

This fantastic filtration system has the efficiency of larger multi-stage filtration systems and the ease of use of smaller cartridge systems.

Let’s see the characteristics of this filter and some reasons why the Marina Slim has earned its place among the best canister filters on the market.

Models of the Marina Slim filter

Marina Slim S10

Marina Slim S15

Marina Slim S20

Characteristics of Marina Slim filters

Compact and extra-slim design

This design offers a slim and compact filter, which is great because it will save a bit of space behind your aquarium. And it gives a lot of elegance to the aquarium.

The Marina Slim is like a cross between a waterfall filter and an internal filter.

In the pictures of this filter you can see how thin it is. The Marina Slim filter is very thin, so it extends along the edge of the tank, but doesn’t stick out as much as other hanging filters.

In fact, it only protrudes 5cm from the tank, making it perfect for tight spaces. Its length, on the other hand, means that despite being very slim, it can still hold a good volume of filter media.

Powerful and adjustable flow

Thanks to its design, the strength of the current is reduced even at maximum flow. And this helps create less current, which means less stress is created on the fish.

Additionally, the filter comes equipped with an adjustable flow control so you can easily control the level of water flow in your tank.

  • Marina Slim S10 – 210 liters per hour
  • Marina Slim S15 – 270 liters per hour
  • Marina Slim S20 – 340 liters per hour

There is a regulating valve located at the top of the inlet tube to adjust the flow rate of the filter, so you don’t have to worry about the water flow rate being too strong for your fish.

The flow level can be reduced during feeding hours so that the food does not spread all over the top of the tank.

High quality filter media

Both cartridges contain Ceramitek (highly porous ceramic), which is a highly porous ceramic filter media that optimizes biological filtration for a healthier aquarium.

These cartridges are pre-packaged fleece pads with some type of filter media. While Bio-Clear is filled with ceramitek and zeolite, Bio-Carb contains ceramitek and activated carbon.

Ceramitek is a highly porous ceramic for better biological filtration. Zeolite is a chemical filtering agent that removes ammonia, dyes, and drug residues from aquarium water.

Activated carbon is an excellent chemical filter media for removing heavy metals, odors, impurities, and discoloration keeping water clean and toxic free.

  • Marina Slim S10 – 1 Bio-Carb / 1 Bio-Clear
  • Marina Slim S15 – 2 Bio-Carb / 1 Bio-Clear
  • Marina Slim S20 – 2 Bio-Carb / 2 Bio-Clear

If you prefer not to use the manufacturer’s cartridges, you can substitute them by other means. Marina Slim filters have enough space to accommodate some ceramic rings even though the internal space of these filters is only designed for use with filter cartridges.

However, if you are not an experienced aquarist it is recommended that you use the manufacturer’s cartridges because they are very good and are worth a lot of money.

Filter cartridges need to be replaced every two to four weeks. It is important NOT to replace all the cartridges at the same time so as not to compromise the biological filtration capacity of the filter.

Pump performance and noise

Comparing this filter to other filters with an external pump, we concluded that having the pump inside the tank greatly helps reduce vibrations.

This filter is very quiet. You’ll need to check for movement in the water to see if it’s on.

As we have said, the MARINA SLIM cascade filter pump is submerged in the tank, which means that it operates very quietly and has a very simple start-up, since it does not require any type of priming.

Some user commented that his filter emitted a certain noise, but in the end it turned out that it was because the lid was not placed correctly.

The pump is quite small and is protected by a grill and a sponge cover. This is great for preventing fish from being sucked into the intake tube, but also prevents large debris particles from clogging the filter media inside.

cascade output

Most backpack filters that hang on the back of the aquarium dispense water back into the aquarium using a waterfall, and the Marina Slim filters also feature a waterfall.

The waterfall on the Marina Slim is not covered like it is on many other hanging filters. And the good thing is that it has bulges along it that seem to expel the water through the surface of the aquarium. A very good idea and useful to increase gas exchange on the surface.

Advantages and disadvantages


  • Slim and compact design for tight spaces
  • A quality product keeps the water clean and clear
  • Ceramitek performs excellent biological filtration
  • The flow rate is adjustable
  • Good waterfall for better gas exchange
  • Automatic start
  • Easy to install and maintain
  • Very quiet operation


  • Filtration capacity is small relative to other cascade filters
  • High cost of purchasing cartridges


On Amazon, at the time of writing this review, we can find 26 customer reviews.

The average rating of all opinions is 3.7 out of 5, that is, a remarkable one.

Of all the clients who have left their evaluation, 56% have given five stars to this filter, and 7% four stars.

9% have scored three stars, 7% two stars and 20% one star.

The vast majority have given a very good opinion about the filter, highlighting how quiet it is, the efficiency of its filtering and its value for money.

Among the criticisms, some reviews comment that the lid generates some noise, and another that the cartridges saturate too quickly.

Other alternatives

Conclusion on the Marina Slim Series Cascade Filter

This is an amazing filter for those looking for a compact and quiet filter. Installation is easy. Just plug and play.

The pump works well and with a few adjustments it runs very quietly after playing around with the position of the tube and cap. There is plenty of room in the baghouse for filter media.

And maintenance is simple and fast too.

The filter itself is very easy to use, hangs nicely behind the tank with a very low profile, generates a powerful flow of water, and is easy to remove and clean.

Rated 4 stars out of 5, this compact waterfall filter is one of the best backpack filters in its class. An excellent, affordable and flexible filter.

If you’re looking for a high-quality filter for your aquarium, consider the Marina Slim Waterfall Filter.

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