Are pump manufacturers dishonest?

[Ichthys]

OK, I am a bit peeved. I am trying to decide on a return pump for my new nano. Pumps i have considered are
Eheim 1250 rated at 317GPH for about $100
Danner Mag 3 rated at 350GPM for about $60
Quiet One 1200 rated at 296 GPH for $30

I have a Quiet One 1200 as my salt water mix and water change pump on my 90 so i thought I would measure its output to see if it really is 296.

For test I put 10 gallons in a 20 gallon aquarium. I placed the QO1200 in the 20 gal with 2 feet of hose attached to the output and going over the lip of the 20 and into a 5 gallon bucket.
I timed how long it took to move 5 gallons and it was 1 minute 41 seconds. In my math that makes the flowrate 178 GPH NO WHERE NEAR the 296 the manufacturer listed. This is a fairly new pump, running under better than normal condition it would run as a return in a system and it ran at only 60% it rated flow!! That really chaps my hide!

Can someone run a similar test with an Eheim 1250 and a Mag 3? I really want to know if this is an across the board standard that manufacturers misrepresent there pump flow rates. If so I am going all class action lawsuit crazy on them. (joke)
But seriosuly I am curious about other pumps, can anyone test their pumps please?

 

[Ichthys]

bump, would really like someone to test the actual flow of a Eheim 1250 and a mag 3

 

[mfinn]

Did you account for the head loss resulting from that 2' of hose?
The flow rates these pumps have are for 0 head with no graviety involved.
Some pumps have better flow rates with less head loss.
No I don't think they are dishonest.
Many pump manufactures have pump head loss rates posted.

 

[seakingaquariums]

Hmmm so all of what I'm going to say below im not 100 percent certain on, but i think it makes sense.

Most standard five gallon bucket hold more water than 5 gallons actually. I Google'd it and the answer i found says they hold approx 5.75 gallons of liquid. then, re extroplating your data, with 5.75 gallons per 100 seconds turns out to be 5.75*36=207 gallons per hour. Which, if you look here Lifegard Aquatics, the 207 gph is pretty close to the 240 gph with 2 ft of head loss listed (this is minus any turns/elbows and i think you could technically say there are at least 2 90's from going up then down into the bucket. , but they actually do not matter that much). So while its not PERFECT is semi- close!

So i'm not 100 percent sure how much water your 5 gallon bucket holds, but the 5.75gallons i had above was just something i found online.

 

[returnofsid]

I'm afraid your test is a bit faulty. So many things need to be taken into account, such as head loss, output hose size, output hose material, friction loss, due to output hose, etc. A pump may 'move' 300 GPH but that doesn't necessarily mean it will 'pump' 300 gph.

 

[JPG@CFI]

Also remember that while the bucket is emptying, the head preasure is getting more. Buy a pump that will get the job done, and move on. If you over buy on the pump, add a ball valve.

 

[Ichthys]

Mag 12 not any better

So today while doing a water change on the 90 gal, i decided to check out the actual flow on my Mag 12 return pump. Now I realize it has about 4 feet vertical and 3 feet horizontal head and also has a few 90's, but I was curious. The flow being returned to the display tank from this 1200 GPH pump was about 340GPH. So I have learned a few things this weekend about just how much head pressure and 90's or 45's effect a pumps performance. All good, just wish I had known before buying the mag 12 a few years back, I would have gone bigger.

With all this in mind I have changed my mind on the return pump I was going to use on my 11 gallon nano. I had been looking at the Eheim 1250 but after all this weekend, I am leaning towards a Dolphin Ampmaster 6200 GPH. Figure by the time it overcomes the head and 90's i might get the 300 gph i want. (sarcasm).

 

[Tecnomage]

What size is your return line for your mag 12? We had a 12. thought it was way under powered so we got an 18 with hardly any improvement. After some searching online I found the mags are really hindered when using < 1" pipe we swapped out the 3/4 and went with 1.5. It made a huge difference, seriously night and day.