Advanced Aquarist: Flow comparison of various powerheads

[Derry]

Advanced Aquarist has a cool article out that shows a direct, head-to-head analysis of the flow rates from a variety of powerheads/pumps, including Aqeon, Hydor, Eco-Tech and Tunze. If the scientific minutia bores you , scroll down almost 2/3 of the way through the article to the bar charts showing advertised vs. measured flow rates.

Of particular interest is the large difference between Tunze's advertised vs. actual numbers (which, per the article's addendum, have been since confirmed by Tunze's own tests in response to the article).

[Mindflux]

It's a real interesting article.. things to keep in mind.

The tests are experimental

EcoTech marine "sponsored" the testing... (probably a nicer way to put it)

This is Roger @ Tunze's post about their methods of testing over on RC:

Where did we get our flow numbers?

We derived our flow numbers in two ways' date=' 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. [/quote']

[Mindflux]

more from roger:

lease read the entire release- we are fixing it' date=' 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.

[/quote']

[Will]

the study was university run, so regarless of funding i dont think that the results are adulterated. Im sure this will be good for tunze, as it will allow them to make their pumps better. Although i wonder about the legality of their claims (on the box) after this data has been presented.

[jestep]

I would like to know if the MJ1200 had the in-tank convertor and not the stock impeller assembly. The specs on it are horrible in every department.

[Timfish]

That was an eye opener! I was expecting to see something around 20% difference from "advertised" flow.

[Robb in Austin]

I am an Ecotech Fanboy but was surprised at the Tunze's results. I was also surprised at the Korala's performance too, as well as the Vortechs.

What I was not surprised by was Tunze's response and I am sure they will correct the "problem".

Regardless, it was nice to see some hard numbers and in real life it doesn't really matter because both Tunze and Vortech are used in top notch systems around the world.

[Mike M.]

Regardless, it was nice to see some hard numbers and in real life it doesn't really matter because both Tunze and Vortech are used in top notch systems around the world.

I agree completely with Robb. The "numbers" don't really matter. Sure they do for arguments sake and "relative" comparison, but honestly, they are great pumps, they move water dependably, and the customer support, especially here in Austin, is fantastic.

I do believe that Roger and Axel with soup up their pumps to bring them near their long time advertised specs, but really, does it truly matter? They can be mounted at a 90 degree angle to the side of the tank. Vortech's can't. That's what they can do that Vortech cant. They are also very, very, very silent and I listen to my MP60 and my new MP10 make their own unique sounds each evening sitting on the couch. So if you want to play the "look at how smart I am" game on internet forums, this article makes good ammunition, in the wet fingered world of reef keeping, these test results don't make a hill of beans bit of difference. I still like my Tunze pumps.

Mike

[mhart032]

IT would be great if they incorporated a footprint vs flow analysis as well. the mp10 is fantastic compared to the others as far as size and flow.