Home TECH SECTION Hydor Koralia G3 eco-friendly and silent recirculating pump review

Hydor Koralia G3 eco-friendly and silent recirculating pump review

Hydor Koralia G3 eco-friendly and silent movement pump review

The Hydor Koralia G3 is a fantastic movement pump: 5,000 l/h flow rate, environmentally friendly with its only 3 watts of power consumption and ultra quiet. What more could you ask for?

Amtra offerte per acquario

We were able to test this pump in our nanoreef aquarium and were able to measure its characteristics. Both situations convinced us, with a bonus that we will discuss later in the article and in our video. So it only remains for us to go and get to know it better.

The Hydor Koralia is a movement pump that has come a long way, and is now in its third declination, hence the name G3. The pump exists in three power variants, 5,000 l/h, 7,000 l/h and 9,000 l/h. We chose the 5,000 l/h version because it was the one that best suited our aquarium.

Technical Specifications Hydor Koralia G3 Motion Pump

Flow Rate
wattl/h x wattDimensionRecommended
freshwater Aquarium
marine Aquarium
Koralia G3 50005.000 l/h3,5 w1.428diameter 7,7 cm x 10,2 cm300-600 l200-330 l
Koralia G3 70007.000 l/h4,5 w1.555diameter 7,7 cm x 10,2 cm400-800 l280-450 l
Koralia G3 90009.000 l/h6,3 w1.429diameter 7,7 cm x 10,2 cm500-1000 l360-600 l
Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa

The Hydor Koralia G3 motion pump video review

Before we get into the technical aspects of our review, we leave you with the video review we made. This will give you the choice of watching the video or reading the article. The two are complementary, so to get a 360-degree view of what we think of this pump it would be great to read the whole article, which has more technical issues, and watch the video. In any case, enlarge the video and enjoy it in 4k! The video is in Italian language but you can activate subtitles.

As we have seen, the pump is given for a flow rate of 5,000 l/h with a consumption of only 3.5 watts. This means that each watt will push about 1,500 l/h, a very good value.


The pump package includes the pump itself and as many as 3 diffusers that are used to expand the flow or to prevent fish and animals in the aquarium from coming into contact with the pump propeller. The spectacular thing, which is the first time I have found in a pump, is that Hydor has indicated the flow rate for each of its 3 diffusers! It is obvious that by interposing something in front of the free flow this would be reduced. But it is spectacular to know by how much! I would also like all the other companies to indicate their flow loss.

Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa: i diffusori in dotazione

In the table below we see the flow rate values. The flow of the pump without any diffuser in front is 5,000 l/h. Then depending on the diffuser mounted it goes from 3,500 l/h to 3,700 l/h to 4,000 l/h. We, in our nanoreef chose to mount the actual diffuser decreasing the flow rate to 3,700 l/h.

Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa: portata in base al diffusore scelto

Why we trust Hydor’s indicated flow rate today – bonus

As I announced in the opening of the article, let’s also talk about a bonus. We all know how difficult it is to measure the flow rate of a recirculating pump. When we’re talking about a return pump, it’s a rather simple operation, because all you have to do is to buy a flow meter, such as our DigiSavant DIGIFLOW 6710M, which plugs into the outlet pipe and, beyond losses and friction, you’re done.

Example of the flow rate of a return pump 
Example of the flow rate of a return pump 

For a movement pump, the issue becomes more complicated than ever. Each company has, over time, undertaken a different mode of measurement. Going back to 2011, there were ways of calculating flow rate by some companies that were described as outlandish by other companies, such as putting a plastic bag in front of the pump and measuring its filling time. That’s why years ago research was done, in collaboration with Penn State University and sponsored by Ecotech Marine, that scientifically measured the flow rate of all the 2011 recirculating pumps.

Perché oggi ci fidiamo della portata indicata di Hydor - bonus

If you want, you can read our article from the time, “Tunze and Vortech…what is the real range of pumps? And how important is this really?” (Italian article) with all the data that came out of the study, but I can anticipate the results that we are interested in right now. The Hydor Koralia 5, 6, 7 and 8 measured at the time, were those whose values were most in line with the declared data. Even for the small Koralia 5, the measured value was significantly higher than the declared value.

Since we do not believe that Hydor has changed its measurement methodology, we are reasonably certain that the values claimed for this Koralia G3 are definitely true.

It works with 15 mm thick glass

The Koralia G3 can be used up to 15 mm thick glass. Expanding the operational possibilities of this pump, and making it suitable for most aquariums on the market. Large and small.

The attachment system to the glass is provided by the famous magneto suction cup. That is, the combination of a magnet and a suction cup. Bringing the best of both worlds. A very solid grip, the elimination of all vibration, and the ability to orient the pump virtually infinitely. A system we have mentioned before that we have always liked very much. Another very convenient thing is the ability to take the pump out of the water while leaving the magnets in place, so you don’t have to find the exact position to put it in every time.

Hydor Koralia G3 free-flowing with magneto suction cup
Hydor Koralia G3 free-flowing with magneto suction cup

If we considered its rated flow rate of 5,000 l/h we could say that it is a perfect pump for marine aquariums of soft corals, LPS hard corals and fish up to 500 liters. Knowing, however, that diffusers lower the flow rate, one can reason with aquariums up to a maximum volume of 350 liters. That is, a pair of pumps that have a flow rate equal to 10 times the volume. Hydor, again correctly, has given 330 liters as the maximum volume of a marine aquarium to be handled with these pumps. If we then wanted to use them in SPS hard coral aquarium the volume would be reduced to about 175/250 liters depending on the diffuser chosen. Of course, always talking about a pair of pumps used alternately.

Speaking of freshwater aquariums, those numbers can be increased again and brought even up to the 600-liter threshold, due to the lower movement requirements that a freshwater aquarium has compared to a saltwater aquarium.

Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa: senza la calotta di protezione

The pump impeller is a classic double-helix impeller, very small considering its size, with its shaft integrated in the pump body. Along the impeller is the retainer that allows solid anchoring to the pump. Assembly and disassembly of the pump are two very simple operations. Very easy to remove the pump from the water, thanks to the magneto suction cup, simple to remove the cap, and then very easy to provide for its maintenance. 

Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa: la piccola girante

What about the noise?

Believe me when I say that this pump is inaudible. You can’t hear it at all. Absolutely silent. And this time we also have a contribution to show you, or if you prefer you can watch the video where we do the live measurement. 

I don’t know if you noticed it by watching the video or looking at the pictures above. But we detected less noise with the pump on than with the pump off. This is obviously not possible. But it is witness to the fact that the pump does not make noise at all, and that the noise generated by the environment may be more important than the noise made by the aquarium pump. Very good result for this Hydor Koralia G3.

To tell if the pump is working, you need to touch the electrical cord… or look at the flow of the aquarium.

Electricity consumption

We started with the review of this pump considering that with only 3.5 watts it is possible to have a movement of about 5,000 l/h. A fantastic result. But again, we proceeded to measure the consumption.

Hydor Koralia G3 motion pump power consumption: less than 3 watts
Hydor Koralia G3 motion pump power consumption: less than 3 watts

In fact, we measured lower power consumption than stated. We were straddling 3 watts, even in the picture above we were below 3 watts. This would mean that a pair of these pumps, kept on alternately 24 hours a day, 365 days a year would have an electrical consumption of 26.28 kwh. And considering the energy cost of 0.27 euros per kwh, we would have an annual cost of 7 euros!!! Truly a pittance! A remarkable achievement for a hobby that is directly related to electricity costs. 


If you have a marine or freshwater aquarium that needs movement, and at the same time you are not interested in having flow regulation, these are the pumps for you. Absolutely inaudible and with 5,000 liters of flow being generated by only 3 measured watts. What more can we ask for from a pump? The flow can be modulated using the supplied diffusers or grates, which make the flow, if possible, even wider and gentler.

Hydor Koralia G3 recensione pompa di movimento ecologica e silenziosa

The only flaw can only be the price, because 89.90 euros official price is certainly not low. Although on the high street, like on Amazon, for example, you can find them at a much lower price. At this price, however, you can get a state-of-the-art pump in terms of very low power consumption and total silence. Hard to do better

Finally, we leave you with a link to our guide on how to best place motion pumps: How to place motion pumps in a marine aquarium – guide (in Italian).


 Small size; 
 Simple and incredibly practical magneto suction cup system; 
 Totally inaudible;
 Minimal power consumption;
 Suitable for thicknesses up to 15 mm;
 Wide and gentle flow;


 The price is to be evaluated;

Hydor Koralia G3 – summary table

Construction quality
Value for money

If you have any questions, doubts or curiosity, I would like to remind you that in addition to leaving a comment below the article, you can find us on TelegramInstagramFacebookTwitter e youtube, whichever social media you prefer. Where you can follow us not to miss all our news, articles, reviews and reports, and if you need to ask for help we are waiting for you in our forum.

Disclaimer: We thank Hydor for providing us with the Koralia G3 pump for this review.

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Ingegnere Idraulico, comincia a scrivere su DaniReef nel 2007, sviluppandolo in italiano ed in inglese, attualmente scrive per il blog americano Reefs.com e la rivista tedesca Koralle Magazin ed ha pubblicato il suo primo libro Acquario Marino qualche anno fa - Danilo is Hydraulic Engineer, began to write on DaniReef in 2007, developing it in Italian and English, currently writes for Reefs.com and the German magazine Koralle Magazin and has published his first italian book Marine Aquarium some year ago.


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