Tunze versus Vortech, what’s about the better flow?
It made quite a debate in the United States an article published in Advanced Aquarist and edited by Michael Sandford, William Straka and Sanjay Joshi, which proposes a new method to calculate the flow of the propeller pumps.
Yes, because in fact the problem has not trivial resolution. How is it possible to measure the true flow from a Stream or a Vortech?
We see therefore this and and other issues, commenting on the cited article.
This changes the state of things? In my opinion no. I do not think this could be the point of the problem.
The study was done in my opinion in a very thorough way, it is not perfect (remember I’m hydraulic engineer;)), but it is very very good. And the fact that it was sponsored by Ecotech Marine I can’t figure it as a low punch. The more information running the better for all, both for hobbyists and for companies. Sandford, Straka and Joshi have tried to emphasize the fact that there is no universally recognized method for measuring the flow of the propeller pumps, and therefore propose this method as a universal method that would have been accepted by all companies, to finally have a touchstone for everyone.
Let us briefly see how it was tested, because I do not want to bore you, but the article is really well done and I recommend to read it Experimental Comparison of Measured Flow Propeller Pumps Aquarium Output of
I will try to mention how the measurement was made.
In short, the water velocity was measured from a diameter away from the pump itself, and then moving along the two axes, vertically and horizontally, until reaching a point where movement was finished using an acoustic doppler velocimeter Sontek 10-MHz. It was then evaluated the contribution of turbulence in a careful way because we stand in a tank in which for obvious reasons you will be mixing the flow of outward and return, it was important to be able to separate the different contributions. So it was also evaluated for how long to measure the speed. Then having the velocity profile on a surface, it has done an integral over the entire surface, which has provided us with precisely the flow.
In addition was measured consumption and propeller rotation speed.
The pumps subjected to measuring was been: Aquaeon 2400, Coralife CP 2900, Vortech MP-10, MP-40 and MP- 60, Koralia 5, 6, 7 and 8, the Tunze 6105, 6205 and 6305 and finally for the purpose of comparison maxijet 1200.
The results that have come out are quite curious:
In blue you can see the declared flow and in green the measured.
The first reading leads us to consider that Tunze have a much less flow than declared, from a minimum of 30% of 6105 up to 55% of a 6305. Vortech instead show an improvement about 14, 18 and 56% for each pump respectively! Good impressions by Koralia very close to the declared flow a part the Koralia 5.
Before commenting on these results, I will do at the end of the article, I would like to get to the end of the original abstract.
In fact, the study also made a chart that shows the efficiency of pumps, namely the gallon per watt, and the consumption of each pump, which is considered at maximum power.
Here you can quickly make some considerations. The measurement of consumption was provided with a power meter, although it is unclear if the meter was able to measure in terms of cos(fi), the phase shift. Apart from that you switch from a maximum of Koralia 7 to a minimum of 6205, without considering the maxijet. Obvious that everything is affected by the flow measurement as above.
Even more interesting, in my opinion, speed profiles, and I quote here only for 3 pumps to follow:
Here it is possible to see the speed profile of two pumps universally regarded as antagonistic, the Ecotech Marine Vortech MP-40 and Tunze Stream 6105.
And from the speed profile it’s possible to note as speed in the center is greater in Tunze, while the flow is more distributed in Vortech. In fact, the top speed of the stream is nearly 5 feet per second, compared with 4 of VorTech. In addition, the flow is much more central. And I must say that this is also reflected by the practice, as I had both pumps, which indeed for a time were also together in my tank.
I also reported, however, the graph of Stream 6205 because increasing power and flow, but having a different shell that distributes the flow, we paradoxically have less speed than 6105 but a much wider and regular distribution than Vortech, although slightly offset in this particular specimen.
The same shell can be mounted on the Stream 6105 thereby leading to have much less central flow, but distributing it more to the sides, more Vortech-style if you will.
In my opinion, however, we have to consider these results together with cost of the individual pumps, because as I have taught at the university, as long as there is no question about costs is impossible to compare 2 items. If the pumps would costs the same the discourse of efficiency would make sense, but in this case …
If we do a little comparison with Ecotech Marine, Tunze and Koralia we get the following prices and economic efficiency (sorry I took the italian prices):
Tunze 6105: 274 euros (Tunze ) and 8.6 gallons per euro
Tunze 6205: 436 euros (Tunze) and 7.4 gallons per euro
Tunze 6305: 626 euros (Tunze) and 5.75 gallons per euro
Ecotech Marine Vortech MP-10: 279 euros (The Reefer) and 8.8 gallons per euro
Ecotech Marine Vortech MP-40: 439 euros (The Reefer ) and 8.6 gallons per euro
Ecotech Marine Vortech MP-60: 729 euros (The Reefer ) and 11.7 gallons per euro
Hydor Koralia 5: 123 euros (Ippopet ) and 21.1 gallons Euro
Hydor Koralia 6: 156 euros (Ippopet ) and 14.1 gallons Euro
Hydor Koralia 7: 189 euros (Ippopet ) and 14.1 gallons Euro
Hydor Koralia 8: 223 (Ippopet ) and 14.3 gallons per euro
That’s bringing in a graph we get a distribution very different from the previous
In fact, the Hydor Koralia win because of its low cost, but curiously, all have the economic efficiency, apart from the fact that Koralia 5 has an extraordinary performance. The Vortech are now much more aligned with Tunze, although the latter are very disadvantaged by this calculation method, however, it happens 6105 becomes perfectly comparable to mp-40 … only randomness?
The article was sent prior pubblication to Tunze and Hydor HQ, and according to the report of Advanced Aquarist the two companies have confirmed the results.
The problem, moreover, as pointed out by the three curators of the project Michael Sandford, William Straka and Sanjay Joshi is that prior to this study, and perhaps even later, this is not the only possible method of measurement. Tunze In fact, for the flow measurement system uses a so-called balloon method, which consists of an empty balloon placed before the pump and then filled with water, from this measurement it’s possible to derive the flow, which obviously must be in line with the data calculated by the project. So the method is not completely wrong, just different, and as such can lead to different results.
But before my comments we move forward with the official reaction of Tunze, arrived quickly after pubblication.
How is it possible to guess, a similar article in a magazine with great credibility as an Advanced Aquarist has created many criticism over the German company, undeserved in my opinion, but this does not count.
So Tunze has responded with a video I report below, where basically they did an introduction in which they explain the importance of a flow is not completely turbulent, a motion in which the velocity vector is pushed in many directions, and that this motion is also what is found in the flow, then took two velocimeter, although different from those used in original study, which measured the flow of two pumps, Tunze and Vortech to the truth, near the pump to the usual distance and at the end of the aquarium.
Then they showed us, in a tank 150x60x60cm, as injecting a dye into the pumps, and even air, it was possible to compare the flow. They did the same thing for homologous pairs of pumps, so for example 6105 against MP-40, and have posted in the video even the direct comparison side by side.
As if to prove that even if the flow was reduced by more than their measured and calculated, the flow quality is excellent.
The result was very practical.
Then if you go to read the notes of the video, that’s very interesting to me, Tunze makes a comparison between the power developed by the pumps, which is very similar, and using the same system to move the impeller, come to conclusion that the transfer of energy between the two pumps and the water is still very similar, so the contribution to the movement still has to be very very similar. I like this way to argument and although there are differences in construction between the two pumps, it is true that efficiency should not be that different. In practice Tunze says that the total flow is equivalent, but the shape is different.
Let’s start with the measurements on the speed, we are sure that this information is so interesting? from an academic point of view I’m deeply interested in these tests, I’m greedy of similar test and they satisfies me so much, I wonder, however, it makes sense to compare pumps that have a flow, to date, so different? More central and powerful Tunze and more varied and distribuited Vortech ? It seems a little how to compare a Ferrari with a Suv, they are incomparable.
Judging from the graphs taken from the first study, in fact Vortech can push in an area with an approximate diameter of 120 mm, a diameter away from the pump, while the Tunze is pushing for about 8 mm, a difference, speaking of the area, more than double.
The data are interesting in any case, but as for consumption declared by the car manufacturers, especially in the absence of a standard of measurement, must always be taken with care, and so it had to do with the data of the pumps. Obvious that from now on by invoking this study will consider the Tunze with a capacity less than that declared, which seems undeniable, and also accepted by Tunze. And every time we will consider the efficiencies we have to think about the measured data by third parties.
Vortech is more wide and Tunze has more power. This has long been known, and this study does confirm the matter. Now the question remains as to which of the two pumps is better, but unfortunately we do not know, as we do not know if our tank needs x-thousand liters per hour of movement, more or less. At the end we reason by convention, and even I do it, and I consider about 20 times the volume of the tank as a movement, so a tank of 400 liters (like mine) would need 2 alternate pumps of about 8,000 liters per hour. In practice, the choice is between 2 VorTech MP-40 or between 2 Tunze Stream 6105, or a pair of new nanostream 6095, two different pumps with different characteristics so that the choice is not easy for me, and I jump from a pair of pumps to another, also considering that by changing the cover of 6105 with that of the greater sister you can get a more distributed flow. In any case, Tunze has responded by saying that in the future will develop an even larger flow.
In addition there is to say that the measurements made by Tunze have always been accepted, not only in the aquarium matters, and so it is not absolutely wrong in principle, only that is different from the method of measurement adopted by the study, so even here we are dealing with two sides of same coin. And then the argument made by Tunze about energy is totally acceptable from my personal point of view.
But in the end, even if it were adopted the method of measurement proposed by Michael Sandford, William Straka and Sanjay Joshi we are sure that the data is so important? If it appears that the 6205 was more similar to the MP-40 … will we take the 6205? I think not … I saw, by testing it in an aquarium, the flow generated by this pump, it’s absurd for a tank of 300-400 liters. So I think in the end, even if these numbers were accepted, would change nothing for us.
I have both a pair of Tunze Stream 6105 and one of Ecotech Marine Vortech MP-40 … (And ultimately a nano stream 6095), yet still can not decide, although in theory I’ve all the tools to do it.
Considering the Vortech MP-40 cost almost twice the Stream 6105, in Italy say about 420 euros the first and 230 euros the second (vat included), true that the controller is separate in the latter, but I expect a pump slightly better by Vortech saw the bill, but not only because it has a flow with wider range. One pump has a wider flow and the other more centered, one is external and takes up less space in the tank while the other is completely inaudible inside, one contributes to warm the tank in the winter so it save us several pennies by contributing to warming and the other is external so it doesn’t helps to warm the tank even in summer, and one is directional one is not.
Soon will come out on my testing on both pumps, hoping that will help you to choose between what I believe the two best brands of pumps currently on the market.
Anyway I am firmly convinced that studies of this type do nothing but improve the tools on the market with great benefit of us all, and help us to know more comparables data to better choose our equipments.