WOW, bad press for Tunze Turbelle
 

Hello:

I saw this article in advanced aquarist... Makes Tunze look really bad...

http://www.advancedaquarist.com/2011/7/aafeature

The short version of this review is that its saying that Tunze is the ONLY manufacturer of powerheads that is providing "less than advertised" flow rates!

In the case of the 6305, its less than 50% of the actual flow!

I would love to hear from the Tunze guys, something must not be considered in this review!

Best,

Estefano

Yeah not good, Would be keen to see what they say.. German stuff is always good :(

I wouldn't draw any conclusions just yet, we don't dispute that we got our flow numbers wrong, I attach our press release about this issue. However, gph is not the only factor at play, to say this is so would be equivalent to saying a 400W MH with no reflector puts out more light and is therefore superior to a 250W HQI with a reflector. I have yet to meet anyone who has done a side by side comparison and not reached the conclusion by observation that our comparably rated pump is stronger, the reason is this ability to direct the flow.



Where did we get our flow numbers?
We derived our flow numbers in two ways, by a test termed a “bag test” and by theoretical calculations. The bag test is just as simple as it sounds, a collapsed bag is placed over the end of the pump and inflated by the pump with water, the time to fill the bag is measured and the flow is calculated. This method has definite limitations, it places backpressure on the pump, and it cannot be used on larger pumps given the limits of bag volume and reliable timing. For all pumps a theoretical calculation is made based on propeller surface area and rotation frequency.
Our bag test results are consistent (within + or – 10%) with theoretical results on the pump models 6015, 6025, 6045, 6055, 6065 and 6085. This led us to rely on theoretical numbers. The biggest pump that a bag test can be performed on is the 6105 and the inaccuracy of flow numbers on the 6105 has a different origin than 6205 and 6305 inaccuracies. The 6205 and 6305 flow numbers were only based on theoretical calculations. The 6105, when released, was near specified flow and was bag tested with a result of 90% of theoretical, however, later modifications to reduce noise relied on theoretical flow numbers and flow was lost to these modifications. On models 6205 and 6305 the fundamental issue is that the theoretical flow cannot be reached due to overly constricted intake and output.
Going Forward.
Over the next 6 months we will perform numerous tests aimed at improving our pumps. We believe pump volume alone does not equal effective flow, the ability to direct that flow is also important. In much the same way as the light available from a bulb means little if it cannot be properly directed into the aquarium, the flow rate at a pump is not as important if there is not sufficient flow at the corals.. We have since purchased two flow meters, one uses comparable sonic technology and the other uses a propeller akin to a common wind gauge and while we have found that using the comparable meter and methodology our results are the same. We have also found the propeller based meter gives divergent data, this data indicates that our more forceful targeted flow draws in current as the distance from the pump increases and that our total flow produced may be well higher than the flow of the pump itself. Use of a different methodology may very well give the opposite results, but this does not dispute the results of this study, it will only show that flow is complex and has numerous aspects which we are only beginning to understand. At this point we conclude that the study is correct for the flow produced by the actual pump itself and we will improve the pumps in a retrofittable manner, though this will take time as new parts must be designed and produced. Improvements will be based on increasing intake surface and reducing output restrictions on models 6205 and 6305 and increasing rotational speed for 6105. We would like to thank Sanjay Joshi, Bill Straka and Michael Sandford for performing this study, graciously informing us of the results and giving input on proposed solutions. We believe it is a step forward in uncovering many of the mysteries of high volume, low pressure flow which until recently was nearly impossible to quantify.

nzsilentone:

I agree with you, I love my Tunze pumps, and for the record... I swapped out 2 MP40s for 2 6205 and I could not be happier!

I would love to see another study from the germans or at the very least some sort of technical document as to how the flow was calculated.

Best Regards,

Estefano

I do truly feel bad for you guys about the bad press, as this may be detrimental to your success, and I never want to see any company in this hobby fail, but how would you feel if you bought a car with the estimated fuel rating of 30mpg and you only received 15mpgs? you wouldn't want the company to say "well we estimated wrong" right! one thing in this hobby seems to always hold true "you get what you pay for"

Please read the entire release- we are fixing it, there will be a solution, but we need time to find the solution. Within 6 months, we will be at or very near the stated flow.

For that matter, the flow is pretty much all there, we tested fixing the shaft on one end and using no propeller housing at all, the flow goes up 20-35% depending on the model. The issue is restriction of the flow by the housing and not some major defect, it is solvable, but it requires redesigning the propeller housing and some tweaks to the propellers. This really is not a huge catastrophe, it is a set back, it stings, it sucks it happened, but we will come out better for this. Imagine if the flow you had from our pumps which you were already satisfied with increased 25-45%? Before this article, I have not seen one single complaint, not one single post, PM or email that the flow does not seem to be what we say, how many posts are there about how much stronger someones 6105 feels compared to there MP-40 or 6055 compared to an MP-10. I think if you step back and just look at this rationally, even go to a store that may have both running in displays, you will see that gph only is a very small part of the story of flow.

Don't worry. I'm still happier with my 6105's than the MP40's they replaced. They're dead quiet and I can direct the flow where I want it. I do wish that the flow numbers were as advertised but get the housing fixed, make it available to the consumer, and we'll be good to go. Does seem to indicate that it's rather important to keep the housing clean of any growth in order to maintain flow.

Mike

Doesn't matter to me..... The numbers are down, yes, but this post by Roger and the way in which Tunze will be handling this are why I have always and will always use Tunze products.

Thanks for the fast response Roger :thumbsup:

You will notice that all the other pumps in the test don't have a pipe bit at the front of the grill, so the flow is far wider compared to the Tunze, so if they cut the bit off i suspect the flow measurement will show a massive improvement.
Maybe tunze can provide two grill ends, one for wide flow like all the other pumps, or a grill that will control the flow as it does currently.

the article stated it quite well, since there is no "standard" for measuring GPH, there will be inconsistency in what each manufacture list as its rating. using the car mpg analogy, if there were no standards for measuring mpg, one manufacture may be measuring it by running the car downhill, so can argue their rating number is correct for the method used.. :) Unless a measuring standard is established, this problem will continue.

I got over 7 different tunze pumps and I am happy with everyone of them. I like a company that stands behind its product and does not hide behind a language barrier and will thats last 6 month old model and we do not have parts for that anymore. A mistake is a mistake it was not meant to deceive anyone.

I hear what D0ugb0y and moondoggy4 are saying... BUT... you have to remember that the ONLY brand of pumps that is below in its numbers is the Tunze!.

I understand that there is no standard but the fact that only 1 company is "off" in their numbers makes me raise an eyebrow to that company...

PLEASE understand that I am not saying that those numbers are incorrect and that I BLINDLY believe that Tunze has to say.

All I am saying is, show me scientifically how Tunze came up with the numbers for their flow ratings!

Coralife -16%
Hydor -1-2%

Not the ONLY ones, but the ones with the worst numbers. What's odd is they didnt' bother to test the Tunze 6025/6045/6055/etc. Which according to Roger do not have the flow issues of their bigger pumps. The study just showed 'the worst of the worst'...

Roger said how they were doing their numbers before up above if I'm not mistaken.

He mentions a bag test.. this is what I imagine that would go like (in my mind)

Determined bag capacity is.. say 20 gallons. Feed the pump water to fill bag. Time how long it takes to fill bag to weight or some capacity line and do some calculations.

If 20 gallons took a minute to fill your GPH would be somewhere around 20*60 = 1200 GPH.

coralife is off with 1 of their pumps by 16%, 1-2% is not even worth mentioning...

dont get me wrong, i am a tunze fanboy too... but numbers are WAY too off for me to ignore! (specially seeing how everyone else's numbers are so close)

Are you running a 61/62/63 series? If not, no worries. The "nanostream" line doesn't have this sort of impact on it.

I probably would not use that as an argument. people have a wild imagination, so I would not compare what someone thinks by feeling the flow to a properly instrumented objective test. There are consulting companies that specializes in damage control and can advise what you should and should not say (just like in the Toyota fiasco, I think they handled their damage control very well).

FWIW, regardless of flow, I am currently a tunze user. I am sure you will come out of this just fine. :)

I just have 6085 delivered today! Just wondering is the flow rate for this pump is off that much as well?

Roger,
Whenever you guys have a resolution, what exactly does this mean to us - the end users? Do we get an upgrade? Is this issue fixable without replacing the entire pump?

There is no big mystery here, the flow was calculated as below, pardon the German, but the math is essentially, prop surface area, times rotation frequency.


Bei der 6305 ist rechnerisch folgendes gerechnet:
Durchmesser ist ca. 51,5mm, Steigung ist 71mm
Rechnung (51,5mm/2)²*3,14*71mm = 147.823,15mm³ = 0,147823Liter
Die Pumpe dreht mit ca. 52 Hz, also: 52*60*60*0,147823 Liter = 27.672 Liter/h, bei einem Schlupf von 20% kommen wir auf 22.137 L/h bei 40% kommen wir auf 16.200L/h
Strömungsgeschwindigkeit: Durchmesser innen bei 60mm, abzüglich Kreuz und Mittezapfen, ca. ø58mm
Rechnung der Fläche: 0,029m x0,029m x 3,14 = 0,0026407m²
Volumenstrom (Strömungsgeschwindigkeit) V= 16,2m²/h / 0,0026407m² /60 /60 = 1,68m/s
Nennleistung: 30m³, V= 3,15m/s

The issue is only restriction of the housing and this is already being addressed, by the end of the year, we will have a retrofittable solution. Look at the large intake and output area of the pumps that hit there numbers, we used smaller intake and output area mainly due to safety concerns of keeping fish, anemones and fingers out. These need to be opened up to allow more flow, we also likely have to increase prop size slightly to compensate for the resistance.

I have never left anybody up the creek and I wouldn't continue to do this job if that was the situation. I value my word and my integrity too much. Give us 6 months, you will see the progress, you will see the solution, if you have an existing pump, we will take care of it.

And re the smaller pumps, 6085 etc, the 6065 is spot on for sure, we measure exactly what we advertise, the 6085 is slightly off, 7600l/h vs 8000 stated (2010 vs 2113gph). The reason is simple the body can handle these flow rates, at the higher flow rates, there is too much restriction, the more you try to force through the more you lose in flow.

Hello Roger,are the 6055's flow correct,would like to hear from you.Thanks Aslam.

Nano Streams all are within reason, for the same reason the 6065 and 6085 are so close, low flow, sufficient area. The effect is the same however so 6025 on one extreme is underrated, 695 gph and it actually does about 750 and 6055 is slightly overrated, stated is 1450, actual is about 1320, but very close. There are no major discrepancies on the smaller pumps and every pump will improve as a result of this research.

It sounds like installing a 6305 propeller shroud would open up the front and simply cutting off every other fin on the back would take care of that side. I think I smell a mod coming.

Mike

OK. Good to know. I hope the upgrade or fix is easy and doesn't requires the end users to pay another premium. Since the "problem" is with the pump themselves, the controller should still work as expected after the fix, correct?

I can't wait for the retro fit, I was already very happy with my 6105's and hope to buy two more very soon!

Will these new shrouds (or what the solution is) be readily available for customers outside of the US free of charge?

Also lets hope the timing isn't like the mythical 7096 firmware upgrade :(

BTW - even though I swapped from MP40's to 6105's and have read the report I wouldn't swap back.