A filter as small as could be: Aqua Medic Multi Reactor S

Un filtro per tutto, estremamente piccolo e che ci è piaciuto: AquaMedic Multi Reactor S

Aqua Medic has released a multifilter, the Multi Reactor S, which is very small and we really liked it. Let’s delve into it together.

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This article is also available in: Italiano

I begin this review by thanking my friend AlexanderGandalf” for lending me his AquaMedic Multi Reactor S filter to write this article.

I have always criticized the many filters on the market because of their size. We have often found ourselves with fluidized bed filters the size of a skimmer. A waste of space that could not be used in an aquarium of, shall we say, household size. With the problem that because of their diameter they were not always easy to place in the sump. So I had already praised a lot the reactor from Two Little Fishies that we saw at Interzoo 2022, the Phosban.

Then I saw this very small filter and fell in love with it. There will probably be many others more or less similar, but I saw this one, so for me, today, it remains the filter to buy. Then, if I get a chance to see others tomorrow, I will talk about them as well. But let’s start with the technical characteristics.

Aqua Medic Multi Reactor Filter specifications

Multi Reactor SMulti Reactor MMulti Reactor L
Dimensions60x50x325(h) mm80x60x390(h) mm100x100x465(h) mm
Total volume270 ml540 ml1200 ml
Useful volume150 ml380 ml800 ml
Consumption4 watt8 watt14 watt
Flow rate200350450
Recommended aquariummax 350 ltsmax 500 ltsmax 800 lts
Max glass thickness12 mm12 mm12 mm
Price97 EUR135 EUR180 EUR
Un filtro per tutto, piccolissimo: Aqua Medic Multi Reactor S - aggancio al vetro

Our video of the Aqua Medic Multi Reactor S filter.

To learn more about the reactor we also uploaded, as usual, our video review, which you can watch on our YouTube channel.

The first thing you think of when you open this filter is… how small is it?! This is its strength and at the same time its biggest weakness. Yes because you have to check very well if its internal volume is sufficient for your aquarium. In fact, the content of the S version is only 150 ml. That is enough for at most a 300-liter aquarium, in my opinion. Although then you have to understand which media we intend to use inside of it.

Yes because the Aqua Medic Multi Reactor S is a filter that can accept anything. From phosphate resins to activated carbon, zeolite to biopellets. Whatever your media, you can safely fit it in here, according to the internal volume available. Actually, the M and L versions have a central separator that also allows you to use two different media inside the reactor. So a fluidized bed filter that can also be used as a zeolite filter. You can put anything in there.

Un filtro per tutto, piccolissimo: Aqua Medic Multi Reactor S - i due cilindri

How does it work?

Its operation is extremely simple. The inner cylinder has two sponges at its ends between which the media to be used must be placed. At the bottom is a perforated disc for the passage of water, which is fed in from below via a plastic coupling below the filter. At the top are holes that drop water into the outer cylinder (left in the upper photo) and out of the lower three holes. By closing the holes with the purple ferrule, water will also drop out from the top.

Un filtro per tutto, piccolissimo: Aqua Medic Multi Reactor S - valvola di regolazione

This possibility makes the filter extremely versatile and allows it to be completely silent. Beware, however, that this is a filter that must be placed inside the sump or aquarium; it is not watertight and cannot be placed externally or you will flood.

The attachment system to the glass panes

The multi-filter can be hooked to the glass panes of the sump or aquarium, as long as they are 12 mm maximum, but I would say there is no problem, for the liters we are talking about. Sumps never go up to 12 mm, and I don’t think aquariums without sumps have much larger thickness.

Un filtro per tutto, piccolissimo: Aqua Medic Multi Reactor S - aggancio al vetro

As you can see from the photos, and especially from our video, accompanying the filter is a plexiglass ring, fantastically finished by the way, which slips on the outside of the filter and is secured by a small plastic screw. I recommend that you don’t over-tighten it so as not to ruin the filter, and I recommend that you always hold the filter externally when you want to take out the internal filter, to avoid ruining it. That said, the ring ends with a C that allows it to be attached to glass of 12 mm maximum. Then there are 2 plastic screws to make the attachment secure. Overabundant for their intended use, by the way.

About maintenance

Un filtro per tutto, piccolissimo: Aqua Medic Multi Reactor S - il filtro

In addition to the size, maintenance is another aspect I really liked about this filter. In fact, by holding the outer cylinder in place, and pulling by the top knob, the inner cylinder is pulled out. At this point you flip it into a jar, and the filter is empty and ready for a second charge. At most you will have to rinse it for a moment to remove all the residue of resins or carbons or whatever else has stuck to the surface. But the whole thing is extremely simplified by the small size of the filter.

Final comments

As we previously said, we really appreciated this filter. Both for its size, which is really minimal, so much so that it can be inserted anywhere, without wasting unnecessary space and volume. And also being able to economize on the power of the pump needed to operate it. 4 watts is really low, even at today’s crazy energy costs. But also and especially because of the simplicity of its maintenance, the real Achilles’ heel, besides size, of this type of filter. Here you extract and throw away the contents. Sic et simpliciter.

The price is honestly low, we are talking about only 95 EUR for a useful filter, and one that you will be able to fit in any sump, whatever size it is. In case you can also find it on Amazon.


Minimum size;
Very simple maintenance;
Very affordable price;
Practical and fast glass attachment system;
Extremely quiet;


Still not sure about the minimum size of 150 ml volume, useful for aquariums up to 300 liters;

Aqua Medic Multi Reactor S – summary table

Quality-Price Ratio

Please note that the Italian distribution of Aqua Medic is entrusted to Funhobby and I can personally assure you that you are in very good hands.

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