Acroholic;528978 wrote: Here is a thread from last year where myself and a couple others tested all three types of magnetic drive pumps with a kill a watt:
1. submersible magnetic drives (Mag Drive, Eheim submersible, Quiet One)
2. external magnetic drives (Pan World/BlueLine, Iwaki)
3. Direct Drive external (Reeflo)
http://www.atlantareefclub.org/forums/showthread.php?t=32071">http://www.atlantareefclub.org/forums/showthread.php?t=32071</a>
What we found was that restricting the output of type 1 and 3 reduced the wattage draw, and that it remained the same for type 2.
But the decline in wattage draw was not proportional I think. In other words, if your mag 9.5 was restricted in flow to the output of your mag 7 wide open, I think you'd still be using more watts that the mag 7 wide open.
I would rather run an appropriate sized pump wide open that restrict one. I am only guessing, but I think it is probably most efficient that way. That is not possible for most folks. I cant do it on my system beause I have to balance flow from one return pump between three tanks, a couple BRS reactors, a denitrator and a calcium reactor. I use a PW anyways. Wanted to use a Reeflo because of their efficiency, but my available space didn't let me.[/QUOTE]
Some what accurate on most Dave. There is a sweat spot on most pumps . That is, somewhere along their performance curve is where they are most efficient. That varies with different pumps. Unless the pump has absolutely nothing attached to the outlet it always has some restriction or head loss. The pump does not know what type of restriction is causing the head loss whether it be a plumbed system with elbows, ts and pipe or a single valve. The best then to do is calculate the amount of dynamic head pressure and purchase a pump whose performance curve is hits around middle ways of that head. A pump with no head pressure running totally unrestricted is usually not operating at it's most efficient rate. the pressure pumps you tested will decrease in wattage used but it is not very noticeable until you are at the top of it's performance curve and only then very little due to it's high pressure design.