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11/09/2017, 05:34 PM | #1 |
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Join Date: Feb 2003
Location: wisconsin
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vectra L1 head loss
Help me understand something please.
I had the unfortunate luck to come home to a seized vectra L1 (using as a return pump). I replaced it temporarily with an eheim 1262 pump -- rated at 900 gph. When running the eheim the flow meter on the return gave me a reading of ~560 gph. (a head loss of about 48%). I just plumbed in my replacement vectra L1 pump rated at 3100 gph. The same flow meter on the same return reads 830 gph. (a head loss of almost 75%). The vectra is calibrated in return mode and is running at full speed. Its the same return plumbing. Even if the flow meter is inaccurate (which I doubt) this suggests a huge difference in head loss as it would be inaccurate for both pumps. For what its worth, the previous vectra L1 gave me a max reading of ~880 gph. Any ideas of why the difference is so much greater with the more powerful pump?
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11/09/2017, 06:58 PM | #2 |
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The frictional head loss (pressure drop) increases with the square of the flow rate. There is a lot more pressure drop (head loss) at 830 than at 560 GPH. There is also a lot more head loss in our piping return systems than we generally believe. Getting more than 800-900 gph from 1" piping is difficult without a pressure rated pump. The published zero head, end of curve, flow ratings that people quote are meaningless unless you plan on using it as a powerhead.
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11/09/2017, 07:18 PM | #3 |
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Thank you, I was incorrect assuming it was a linear relationship.
Damn you physics.
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11/09/2017, 10:47 PM | #4 |
Grizzled & Cynical
Join Date: Apr 2006
Location: Stamford, CT
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Further, the Vectra pumps are designed for flow not pressure, thus they drop off faster than one that prioritizes pressure over flow. For example, my panworld 200 pumps only loses 20% pumping up 12 feet in my system - because that's what it's designed for.
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Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs |
11/10/2017, 08:56 AM | #5 | |
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Join Date: Jan 2012
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Quote:
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Fish are not disposable commodities, but a worthwhile investment that can be maintained and enjoyed for many years, providing one is willing to take the time to understand their requirements and needs Current Tank Info: 625g, 220g sump, RD3 230w, Vectra L1 on a closed loop, 3 MP60s, MP40. Several QTs |
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11/10/2017, 03:23 PM | #6 |
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Join Date: Nov 2002
Location: Miller Place, NY
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DC PUMPS have problems with head pressure.
Abyzz & Red Dragon pumps are the exception.
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250 gallon mixed reef, 2 Reefbreeder's Photon V 2, Deepwater BLDC 12, DAS EX-3 Skimmer, MTC mini cal, 2-3/4" Sea Swirls, Aquacontroller & 6 Tunze pumps. |
11/11/2017, 04:31 PM | #7 | |
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Location: wisconsin
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Quote:
That explains why they sent me a replacement without any question about mine failing. It’s out of warranty and they didn’t even blink an eye. It’s probably time for a red dragon. I’ll get the flow I need. I’m just disappointed given how expensive it was. I’ve had eheim and mag drive pumps running on other tanks without any maintenance for years. Sent from my iPhone using Tapatalk
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11/14/2017, 07:18 PM | #8 | |
Saltwater Addict
Join Date: Jan 2012
Location: Vandalia OHIO
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Quote:
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Fish are not disposable commodities, but a worthwhile investment that can be maintained and enjoyed for many years, providing one is willing to take the time to understand their requirements and needs Current Tank Info: 625g, 220g sump, RD3 230w, Vectra L1 on a closed loop, 3 MP60s, MP40. Several QTs |
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11/14/2017, 09:59 PM | #9 | |
Grizzled & Cynical
Join Date: Apr 2006
Location: Stamford, CT
Posts: 17,319
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Quote:
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Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs |
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11/19/2017, 07:13 PM | #10 |
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The largest eheim pump (a 1262) gave only ~550 gph through my sump. Thats only 1.5x turnover for me.
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