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Exclusive: Hagen responds to Fluval G critics

Robert Reid, Hagen's category manager. Pictures by Dan Crawford.

The launch of Hagen's Fluval-G external filter met with a mixed response from Practical Fishkeeping readers.

Following our report covering the launch of the Fluval G (see Hagen announces launch of Fluval G filter some readers criticised several aspects of the filters.

Many were impressed with the appearance and design of the filter, and the incorporation of innovative features such as an easy-to-clean cartridge system and computer control unit, but others felt that the filters included features that were non-essential.

We spoke to Hagen's category manager Robert Reid who clarified some of the points raised.

We are currently testing the Fluval G range.

Check out the Christmas issue of Practical Fishkeeping magazine for our full in-depth review.



It's great that Hagen has been so innovative and launched such an interesting product, particularly given the current economic climate. Who do you see as the target market for the Fluval G range?

We strongly believe that there are a lot of people out there, interested in buying and owning the latest technologies or products that make life easier and are more convenient. As long as there is good value for the money the savvy consumer will be as excited as we are to experience the Fluval G. A good example would be those consumers buying Apple products, such as the iPods or iPhone. They could purchase similar performing items for less but don't because they see the intrinsic value. And this is exactly our target group. They could be beginners, intermediates or advanced fish keepers.

In addition, the development of the Fluval G should be considered a milestone in filtration technology, and it will definitely raise the bar for other filter manufacturers to rethink their strategies and designs in order to produce easier and more consumer-friendly products. The Fluval G will definitely change the way we look at aquarium filtration today and without any pioneering work, we would still be in the age of air pumps and under gravel filters.

The first thing many people have noticed about the filters is their comparatively low flow rates. Several years ago there was a trend for using low-flow rate filters, particularly on planted tanks. However, many people, especially in the planted tank community, are now going for higher flow rates in order to get better suction and cleaner tanks. What was the reason for making them so low?

First of all, people must understand the difference between flow rates and filter circulation. In all reality the motor performance is "useless" information for aquarium keeping as it's a motor only performance value with no hosing, in-tank accessories or filter media and who will ever use the motor-pump that way?

The useful information is knowing how much water the filter processes but most manufacturers only mention the actual pump or motor performance (flow rate) on their packaging, without pointing out that this is not the same as the actual circulation rates once all the filter media is added and the pump must perform under full load.

To be looked and compared in the same light we’ve been forced to follow suit however, if you do a real comparison our pump/motor performances (flow rates) and guaranteed filter circulation rates under full load are actually higher for the recommended aquarium sizes than most other manufacturers.

The Fluval G3 has a pump performance of 1285 lph and a filter circulation under full load of 700 lph; the Fluval G6 has a pump performance of 2460 lph and a filter circulation under full load of 1000 lph.



If the flow rates are not actually low, compared to competitors' filters, why have you started quoted flow rates differently with the Fluval G range? Is it this change in quoting actual flow rates rather than maximum flow rates that has caused confusion among readers?

I think we've covered this but once the reader understands the difference between pump performance without any load and filter circulation under full (hydraulic) load, this question will be automatically answered. Rather than confusing the consumer and indicating values that have no relevance, we are telling him exactly how much water is actually circulated within the filter. Fluval canisters have always declared both these values just go to www.hagen.com and all the information is there.

The addition of a conductivity meter is unique in the aquarium market. Do you think customers will be able to understand how to use a conductivity meter to inform them of the need to conduct a partial water change, and don't you think that the benefits of this might be cancelled out for those people who make water changes regularly? Surely conductivity only rises noticeably when maintenance is lax and frequent evaporational losses are present. Isn't it going to be misleading for anyone with an open-topped aquarium?

This is purely an educational process, and I will explain. One of the most important issues for aquarium keepers is providing and maintaining a suitable and stable environment for living organisms; conductivity is thus a very important parameter to be monitored, as it provides a general but fundamental alert that something is changing inside the aquarium. It is something similar to the body temperature of a person. A deviation from the "normal" range does not point at a specific pathology but suggests that something is changing or has been altered and needs to be accurately investigated.

In nature, every biotope can be identified by a complex list of interrelated characteristics; in aquatic environments, conductivity is a very important one. Fish are very sensitive to this value since conductivity is strictly related to the amount of osmotic pressure exerted on our fish’s cellular membranes, and they are well adapted to the specific conductivity range of the environment in which they live or from where they come. This is why it is essential that any fish you are adding to an aquarium are suitable to the water therein. Otherwise, your fish need to continuously pump fluid in or out, so that the osmotic pressure is equalized across its cell membrane.

Remember! Different species of freshwater fish require different conductivity values that can range from 100μS to 1000μS. Breeders have known this for years.

More and more hobbyists constantly check the conductivity values of their aquariums as a way to understand at a first glimpse that something is changing and consequently start deeper analyses using various Test Kits.

Nevertheless, if a consumer observes the conductivity levels for a few months, at the same time measuring GH, nitrate and phosphate levels at different times and different conductivity levels, in the end he can roughly derive from the conductivity value how much these levels have increased in his particular aquarium.

For example, lets say we tested the conductivity value in a 70 litre aquarium, starting with a value of 250μS/cm and this level increases by 30% to 325μS in 40 days. We then perform some chemical analyses, and clearly determine that at least one part of this increase was due to Nitrates which in the same period had risen from 23 to 40 ppm as NO3-. By simply making a 30% water change we could re-establish the original values to around 250μS/cm.

And by using the Hydrotech Performance Monitor, we could now set a maximum "alert" value for the conductivity at a level of 300μS, simply understanding that it’s time to perform a water change.

For a saltwater aquarium the integrated conductivity meter is a must and extremely convenient, since it will make hydrometers or other salinity measuring equipment redundant.



We assume that conductivity rises with time because of evaporational losses. When these are not topped up the concentration of dissolved minerals in the water rises which increases conductivity. In a well-maintained tank that sees regular water changes and top-ups, conductivity fluctuations may be minimal. Does this follow your opinions on the topic?

I think we need to delve a little deeper. Rises in conductivity values in aquaria are caused by increases in ions. Sources of additional ions or higher concentrations of ions do not only come through evaporational losses but from anything added to the aquarium for example foods, fertilizers, pH stabilizers etc. However conductivity can also be influenced, positively or negatively, by gravel (some gravels bind ions) or negatively by heavy nitrification. Aquariums are complex living biotopes and because of their limited size water chemistry parameters are greatly influenced by small activities that would not have any bearing in the wild.

We could assume a regular 10-20% water change with demineralized water will negate the addition or decrease of the various ionic sources but without testing all parameters we cannot be sure. Was a 20% water change sufficient or was a 50% water change required? As mentioned each aquarium biotope is unique and complex and in each case water sources differ, feeding habits differ, feed types differ, planted aquaria vs. non planted aquaria and so on but we as an industry cannot make specific maintenance recommendations for each and every tank set-up rather, we can only generalize maintenance procedures. In the long run a generalized maintenance procedure will not solve all the unforeseen woes.

By adding a conductivity sensor with graphing capability one can get a sense of what the "normal" operating conductivity measurement is for ones own "unique" aquarium. Then once comfortable with the system and the normal range, increases or decreases in value tells the user something is out of whack and further investigation is required.

It is similar to say a thermometer, when it reads 36.5 °C it's telling me that my body temperature is normal. When my temperature is higher or lower (hopefully not) it's not a specific diagnosis but an indication that I need to find out what the problem is. I am convinced that once one is familiar with the system and the reading trends, it will become an invaluable tool to maintaining proper water quality as well as providing some peace of mind that all is normal and the water characteristics are appropriate for the fish species.

You say the conductivity will not need to be recalibrated. What happens if it gets covered in lime scale?

We know that conductivity meter instruments normally require periodical calibration. However, when designing the system, our goal was to simplify the life of the user and to develop an instrument that would not need recalibration. Just remember that calibration normally requires plunging the probe into a solution with a known conductivity value.

With this goal given, our R & D team worked on the mechanical and electronic core of the instrument for many, many months to finally focus on an original and innovative solution that has been tested extensively for 1.5 years now.

The final solution provides precise readings within the declared tolerance, guaranteeing a calibration-free system. A year and half of testing in various aquarium settings has given us this proof of reliability.

This is accomplished through a high quality sensor which assures high stability in both marine and freshwater aquatic environments, a well-studied circuitry and innovative software which includes special algorithms to process data and consider system tolerances.

Of course the presence of an integrated thermometer is strategic for the self-adjustment of the instrument to temperature variations, which have a sizable impact on conductivity measurement (any quality conductivity meter should normally have an integrated thermometer).

Let me also add that independent conductivity meters are normally developed to provide accuracy on a very wide range of values and types of solutions, not necessarily being specific for aquarium use. The advantage for us was concentrating on two specific ranges (marine and fresh water), which has resulted in a very robust and calibration free system.

In particular, the titanium sensor pins have demonstrated their full functionality after 2 years of specific testing in various aquarium environments. As for the possibility for the pins being covered in lime scale, this is a very remote possibility considering the operating conditions of the filter, as calcium carbonate tends to precipitate over "warm" surfaces (compared to the temperature of the surrounding water).

Our sensor pins work as "cold" surfaces and once the filter is in operation and water flows through them, there is really no chance for calcium carbonate to precipitate. Besides this, sensor pins are self-protected against such phenomena as electrolytic depositing and passivation, thanks to the way they are activated by the electronics, with frequent but short-time cycles. This way of operating is another reason why there is no need for instrument calibration.

Measuring conductivity accurately is a complex task as there are many factors at play, temperature being just one. In the Fluval G the conductivity monitor becomes increasingly more precise after 24-36 hours from power-on, as these factors become more stable. For this reason, it’s best to limit any contact and just rinse the sensor area with clean water every once in a while.

Why no pH monitor?
We thought about this of course, and there are basically two ways to do this. The cheapest way would be using a traditional glass probe. However, since the pH sensor, like the temperature and conductivity sensors, has to be installed underneath the filter lid, the glass would be exposed and could easily be damaged. Consequently this was not an option for us.

The second way would be employing a special chip technology which would have increased filter cost by 20-30%. So this was not an option either. Nevertheless, this is another challenge that we are facing and might be able to tackle in the future.

A large proportion of PFK readers would have liked a heater built in. Did you consider this feature and if so why not?

Of course we did. But again, any feature we would have added would also have increased the cost and we were looking for the best consumer mandated value for money...so we had to make some decisions. Considering Aquariums heaters have become a commodity we opted for the EC monitor. We've noted some PFK readers have been surprised by the retail price, but I need to point out that a decent conductivity meter retails for around £ 100.00.

Nevertheless, we have already installed a connection point that will enable us to add an external G heater and it is already integrated to the HydroTech software. This will be the next step in the Fluval G Evolution and be one of the first add-ons. [Other heaters cannot be integrated or connected to the Fluval G and the G-heater is not yet available.]

Do you have any plans to launch a larger G9 or G12 model?

Anything is possible, but let’s wait and see how the market and the consumers react to the first two models.

With the modern demands that we place on external filters, like crowded cichlid communities, large predatory fish and marines, why was a model not produced that had the dirt and flow capabilities of the FX5? Say an FX2, FX3 or FX4?

The Fluval FX5 is a big beast and rated for a 1500L aquarium and I must say it's a fantastic filter and was well received by the aquatic market but how many 1500L aquariums are out there? But I do realize not everyone is using it on a 1500L aquarium as I know guys using it on a 200L aquarium. So there is always a good chance that there will be additional models. It all depends on the market requirements of the time and customer demand.

To find out what we think of the Fluval G, check out our exclusive in-depth review of the filter in the Christmas issue of Practical Fishkeeping magazine. On sale next month.

This article may not be reproduced without permission.

Matt Clarke: 16.10.2009
Views: Read 4,031 times


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