Blog Comments

I found the first hints of cyano algae again today It's too bad. I've been keeping up with pretty good water changes over the past couple of months - but I noticed today at a couple points of intersection between corals where some chemical warfare had heated up a bit, cyano now coats the junction. I'm going to be patient with this one - maybe it's feeding off the dead coral and will subside. If not, I'm going to turn off the bio reactor and see what happens.

Yeah - I tend to agree. Probably got a 'hot' motor. Working in the electronics industry, I guess it doesn't surprise me too much to see something deviate from spec by +/- 10% - that's a pretty common tolerance. ...or possibly the kill-o-watt came off the assembly line in china at 5:00 on a Friday. The tradeoff of the 'hot' motor scenario is likely that my motor can handle an equivalent head load of 10% more and also gets hotter. Not a big deal. What I'm more worried about (since the dart impeller seems to be close) is that the snapper impeller performs ~25-30% above spec - which is wasted energy from my point of view. Makes me think there's an impeller specific defect there. I requested a new snapper impeller - we'll see if I get one.

It seems as though your motor isn't cutting the mustard, compared to me and fridmani1. As far as I know my two snapper/darts have the standard motor in them. I did not ever specify a gold version.

More data - Using the kill-o-watt:

Wobbly snapper impeller:
mostly open, but under load - 135W
completely closed - 119W

Dart impeller:
mostly open, but under load - 155W
completely closed - 135W

New bushing on impeller (no longer wobbly):
Same as the wobbly version...

Cool! Thanks for the data. I'm going to do a bit more with measurements on my system. Today, I got my hands on an actual kill-o-watt so I can make sure we're comparing apples to apples. Fridmani1 - I was just at the reeflo site and it looks like the GOLD version is supposed to be the same efficiency as the standard if you look at the standard snapper impeller setup.

Ok, I found a Kill o watt meter at home depot. I am getting 145 watts with my pump wide open and about 6 feet of head. When I closed the valve all the way I was getting 125. This is running the Dart impeller.

I also tested my salt tank pump:
Model 100PX - equal to Iwaki MD40 Pressure rated
790gph max flow
21 foot max head pressure
120 watts
3/4" MPT in/out
Footprint 5 x 14

it measured 100 watts at 7 feet of head

No meter at the Lowe's, I will have to order one. I am curious how mine compares.

I have a regular or the "real" kill-a-watt and I have a Dart impeller on my Reeflo pump.

I've never actually connected the pump to the kill-a-watt before so I thought I'd give it a try. I have the bluefin motor since I have a problem with my original pump where if it lost power it would not restart on it own. I would have to manually turn the screw on the back to get it going. Since I was getting a re-built pump in replacement I asked if I could have the motor that came with the "Gold" version of the pump. They said yes and here are the results that I found with this motor:

Pump wide open: 145 Watts
Pump about 60% 125 Watts
Pump closed: 115 Watts

So it seems that this motor might be more efficient. What motor do you have on your pump?

http://www.amazon.com/P3-Internation...=measure+watts

I think they sell these at Lowes and Home Depot. I got a cheaper knock-off at Lowes.

The kill-a-watt is sophisticated enough to factor in time whereas the model I ended up purchasing only takes and instantaneous reading.

Where would I be able to find a meter locally? I will hook it to my dart and check it

Blennyman, the only way to actually tune the pump for best efficiency is with a kill-a-watt and flow meters....you can come close enough for most things with calculations, but to find the best efficiency for your system at your altitude you have to actually take "insitu" measurements...remember as the pipes slime up and "stuff" builds up in the pipes, the friction coefficients will change and the efficiency will have to be retuned all over again...tough but that's the way it is...so usually calcs are close enough

My $0.02

Blakew

BTW, blake - I DO have a kill-a-watt somewhere at home and will certainly be running some numbers with the various states of valve closure. Unfortunately, it doesn't do a whole lot of good to measure this without measuring the head and pipe resistance as you alluded to earlier as it's all relative to the delivery system. I'll do my best though...

Ah - I haven't been logged in to see the hoopla! Blakew actually caught me on one thing. I had the impeller names reversed. The Snapper is actually the smaller one, the dart is the larger one. My original question (I must admit I asked it before drawing some efficiency curves or knowing how for that matter) had to do with finding the best efficiency point of your pump - i.e. getting the most work (the physics term) done per watt. After stewing on it for a night, I understand how to calculate everything on paper, but I don't have a way to "tune" the output restriction valve to the BEP. I can probably wing it and get sort of close with a kill-a-watt assuming the power numbers advertised on reeflo's website are accurate, but my original question was whether there was a simple way to do this in the midst of a system with a complex manifold and several different drop points set up.

I'm an engineer! I like efficiency!

Hi Joeogio,

My guess is the marketing claim would be that by spinning less rpm (higher head, less flow, impeller doesn't spin as fast) the seals wouldn't wear as fast, which would seem a reasonable statement.

Blakew

PS If anyone has a Snapper/Dart Hybrid and has a kill-a-watt, I'd love to see what wattage they're actually drawing, cause if they really are drawing 100 watts at 1500 gallons per minute they're pretty damn good. Most of the other pumps don't provide a breakdown of wattage at specific flows like Reeflo does, however, based on max wattage draws, in the few mins I've searched the pumps that can produce similar flows at similar heads as the Snapper, use quite a bit more electricity. So I'm willing to eat my words about wattage draw in the interest of making sure other reefers are helped. It would seem based on published data that using the Snapper impeller on the Snapper/Dart hybrid is more energy efficient than most pumps that can provide similar outputs even when using a partially closed gate valve to restrict the flow. Nothing I found that could provide 1000-1500 gph at between 6 and 9 feet of head came close to matching the published 100 watt draw. Would really love to see someone plug one in to a kill-a-watt and see if it draws more than 105 watts or not.

i curious to find out how it helps save the seal maybe less vibration? anyone know?

The statement from the manufacturer is a sales statement. What I mean is they're saying to someone who doesn't need 1500 gph flow through their overflow, "you can still buy this pump and just strict the output so that it's only flowing 1000 gph". In the "real" pump world it's a bad idea. You only get the pump that's big enough to do what you need it to do and no more. What I mean is, if you need 1000 gph at 7-feet of head you don't buy a pump that produces 1500 gph at 7-feet of head and restrict the flow until you get 1000 gph at 8.5 to 9 - feet of head. The pump that produces 1000 gph at 7-feet of head will in almost every case use less energy than the pump that produces 1500 gph at 7-feet of head (even if the second pump is restricted so that it only flows 1000 gph).

As for the car exhaust comparison, you are correct, without some restriction the pump will over rev and you risk cavitation, but just like with a car exhaust if you restrict the exhaust flow too much you loose performance. That's why "johnny go fast types" pull the factory exhaust off of their sports cars and add aftermarket exhaust that are less restrictive. When they do, they get better performance.

Blakew

See I think that trimming, might be what he was looking for, but, blenny hasn't posted since the first. It seems as though the manufacturer even recommends trimming the output to save seals and energy, like its not meant to be wide open. Kinda like exhaust for a car is supposed to have some resistance.

Not to beat a dead horse, but the title of the blog was "Tuning a Pump for BEP (best efficiency point).

If the goal and intent of the post was to find the point of lowest energy usage then as stated above stick a valve inline and dial back the flow to the minimum flow you're willing to live with.

If the goal and intent of the post was indeed to find the point of best efficiency, that's a horse of a different color.

Pump efficiency in simple terms is how much of the energy put into the pump is converted into useful work. To find the point of best efficiency you'd need an efficiency curve, but we can estimate that point by looking at how much flow the pump is producing.

For the snapper, comparing the first two published data points from the pump curve we get a 14% reduction in flow for a 105% increase in wattage used (not very efficient going from 0-foot of head to 2-foot of head, for the next two data points we get 16% reduction in flow for a 105% increase in wattage used, for the next two data points we get a 20% reduction in flow for a 5% reduction in wattage used (now we're going in the right direction), for the next two data points we get a 40% reduction in flow for a 5% reduction in wattage used (wow fell off the earth on that one), for the next two data points we get a 67% reduction in flow for a 26% reduction in wattage usage.

Based on this information the most efficient operational point is going to be between 1900 gph and 1500 gph. If your current set up is pumping more than 1900 gph and you're willing to live with the reduction in flow, you could dial the gate valve back until the pump was producing somewhere between 1900 gph and 1500 gph and you'd be in the ball park of the most efficient operational point for that pump with your system.

Blakew

You can however lower the consumed wattage on the pump, just not to the point where it would be better to throttle back the dart instead of using the snapper.

Now we're on the same page. Absolutely agree with this statement.

More to the possible intent of the original question, based on Reeflo's published data, you can reduce the wattage consumption on the Snapper from a max of 105 watts to a minimum published wattage draw of 70 watts, if you're willing to reduce the flow from 1500 gph to 300 gph.

The only way to know absolutely for sure how much power you're saving is to partially close a valve on the pressure side of your pump and check the wattage draw with a kill-a-watt (you could come real close by doing some calculations). If you're willing to have less flow, you can save some energy. The reduction in flow will be much greater than the reduction in energy costs, but you will save some energy.

Blakew

Ok, Blennyman, what is your question based on? Blake is correct that you cannot make the Dart version consume less power than the snapper. You can however lower the consumed wattage on the pump, just not to the point where it would be better to throttle back the dart instead of using the snapper. I agree with Blake in his point about the flow vs power consumed.