This may be a pretty basic question, but I haven't been able to find an answer. When it comes to AC pumps versus DC pumps, the only DC advantage I can find is the controllability factor. I see several recommendations saying buy bigger then dial it back, especially with return pumps. My question is, couldn't the same thing be accomplished by dialing back an AC pump using a gate valve? WHat am I missing?
AC versus DC pumps
- Thread starter Pete Paschall
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Using a gate valve will reduce the water flow, however it will not alter how hard the pump is working. A DC pump controller alters how hard the pump is working.
Peace River
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Another related thought to throw into the conversation that @Brew12 shared with me at MACNA and then made a similar comment in the quoted post that is copied below:
I can think of a few other advantages of DC (and vice versa)
a) DC pumps run cooler IME. I loved Mag (Danner) pumps but they add a lot of heat. Results can vary.
b) DC pumps can soft start versus blast start
c) DC use less watts and amps. Results can vary.
d) DC can be programmed for feed mode that does not back siphon
On the flip side, I've run a couple of AC (Mag 9 & 18) pumps without issue for 10 years so we will see if my DC pumps hold up like that. I have DC pumps for all returns and the old ACs now do the heavy lifting and mixing work.
And now that I have read @Peace River post I have added the caveat "Results can vary" depending on what pumps you are comparing.
a) DC pumps run cooler IME. I loved Mag (Danner) pumps but they add a lot of heat. Results can vary.
b) DC pumps can soft start versus blast start
c) DC use less watts and amps. Results can vary.
d) DC can be programmed for feed mode that does not back siphon
On the flip side, I've run a couple of AC (Mag 9 & 18) pumps without issue for 10 years so we will see if my DC pumps hold up like that. I have DC pumps for all returns and the old ACs now do the heavy lifting and mixing work.
And now that I have read @Peace River post I have added the caveat "Results can vary" depending on what pumps you are comparing.
Dr. Dendrostein
Marine fish monthly
DC more precise and energy efficient , but can't beat a Eheim pump that's 20+ years old and still ticking.
That's what I have.
biggest advantages to me if comparing each as a basket of pump types together.
Returns-
DC are usually quieter. Also love danner pumps, they will take a beating and keep ticking. But man do they vibrate without some careful planning like a small amount of soft tubing between pump and pvc.
Variable speed is easier to adjust to an over flow than a gate valve. Both can achieve no gurgle sound, the controllable pumps require less playing around.
Circulation pumps
This is where dc shine imo, i love hydors they last at least 5 years with very basic cleaning. But to create variable flow with just ac pumps they need to start and stop abruptly, creating cavitation you will definitely hear. That said can definitely decrease total cost of pumps if mix them. Have say 2 controllable pumps that vary the flow and 2 wide angle ac pumps constantly on that add to the total flow.
Returns-
DC are usually quieter. Also love danner pumps, they will take a beating and keep ticking. But man do they vibrate without some careful planning like a small amount of soft tubing between pump and pvc.
Variable speed is easier to adjust to an over flow than a gate valve. Both can achieve no gurgle sound, the controllable pumps require less playing around.
Circulation pumps
This is where dc shine imo, i love hydors they last at least 5 years with very basic cleaning. But to create variable flow with just ac pumps they need to start and stop abruptly, creating cavitation you will definitely hear. That said can definitely decrease total cost of pumps if mix them. Have say 2 controllable pumps that vary the flow and 2 wide angle ac pumps constantly on that add to the total flow.
ca1ore
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The cynic in me wonders whether the whole DC pump thing is a ‘massive’ con job. Are they really more efficient, or just designed to move maximum amounts of water at very low pressure levels. Take the AC PanWorld model 50. There are two versions, the PX that moves 590 gph and the PX-X that moves 1,100 ..... both draw 90 watts. Latter MUST be more efficient right? In low head pressure applications, the PX-X is likely the better choice, but it craps out much more quickly when you add head pressure. The only build difference is the volute/impeller design. No reason the current crop of DC pumps couldn’t design pressure-rated pumps ..... but then, of course, they wouldn’t ‘seem’ quite so energy efficient LOL. Personally I’ll take a proven pump that’ll last me 15-20 years ..... THATS what drives low total cost of ownership.
delv2323
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Restricting the flow on a DC pump will reduce the amount of energy it draws and ramp down its power. A properly sized AC pump should run for many years. I like anything based on the Laguna blocks (Skimz, Red Dragon, Vertex).
jeffchapok
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In my experience, DC pumps are much quieter. I can't even tell my return pump is running.
So to answer your question as everyone has pointed out. No you cant accomplish the same thing on a ac pump to reduce flow by using a gate valve to reduce flow.
The ac pump is either on or off and wattage use will show you that. To reduce flow if you use gate valve head pressure will increase as people have told you and load on pump increases ......
On dc pump to reduce flow you step the motor down via power thus you are using less power consumption and everthing everyone has stated......
The end result of less flow is acclomplished. Yes. But they are very much different in how they get there. For all the advantages of dc pumps that are listed here. That is why i switched and love it. There is no comparison imo.
I have used some of the best ac pumps and they done a great job for me with no issues. Now my dc pumps are doing a better job.
The ac pump is either on or off and wattage use will show you that. To reduce flow if you use gate valve head pressure will increase as people have told you and load on pump increases ......
On dc pump to reduce flow you step the motor down via power thus you are using less power consumption and everthing everyone has stated......
The end result of less flow is acclomplished. Yes. But they are very much different in how they get there. For all the advantages of dc pumps that are listed here. That is why i switched and love it. There is no comparison imo.
I have used some of the best ac pumps and they done a great job for me with no issues. Now my dc pumps are doing a better job.
330Bob
Community Member
Hehe well DC has more WOW to the new hobbyist for sure. It adds cool settings that can be controlled via phones or internet. Even in 2023 its still a valid question, just got asked the other day in a store.
I've had both for 25 + years.
For pressure working against a head - nothing beats AC Iwaki, Panworld and other commercial grade pumps. they just last and are not picky on power fluctuations. There is not delicate computer integration, fewer delicate connections to go bad. Not to say you can't get a cheap AC pump. Usually its the housing leaks and short out. I prefer to run the AC in the air with PVC plumbing so very little heat is added.
AC - External for returns and pressure. Yes on longevity, (15+ years) the bearings can be rebuilt too. Yes to low heat, Yes for working against head vs DC. And they will draw less power if you cut flow. I tested on and it dropped 80 watts cutting the flow with a ball valve. Don't get excited it does not go to ZERO watts.
DC - For submergible they seem to put less heat in to a tank. I put them on a Sine wave ups to protect the delicate computer boards from surges. That is the weak link. I have them going for 5+ years so they can be reliable.
Build quality is not close vs commercial pumps. Its like A Kubota tractor vs a home depot special no contest. AC win.
I think a high head AC external + manifold is solid and reliable. Like Iwaki or panworld 200ps 1500- 1800 gph that does not drop much under head (12 feet is nothing)
DC - Good for Light duty low head. Powerheads for huge flow and wave functions are nice and can be reliable. I've have some running 5+ years no issues. But I put them on a Sinewave UPS so their controllers do not take hits from dirty power. I've blow a few just running on power strips.
Most the people I know like to run DC but they also go through pumps like cell phones. Like 3 in 5 years is like "Or well things wear out" So if that is all they know they think its normal just tossing out a cell phone every 2 years.
Not to say DC can't last, they can but I would not put them at the top of reliability long term, there is just more to go wrong.
ca1ore
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Had to go back and look to see if I still agree with that 2019 post LOL. I actually do. My Vectra M1 recently died after 8 years. All of the pan world pumps I run of similar vintage are still going strong. I cannot really be bothered to calculate electricity savings but I doubt it’s the cost of a new vectra.
I think that is the problem that most people do not bother and do not look at the facts. Here are the cold hard facts based on 2 pumps (1 AC and 1 DC) running at 100% 24/7 for eight years. this is not getting into the M1 having flaws and replaced by M2 which should have longer life span and heat dissipation, etc etc etc.
Here you go for your own future reference of where your money is going. If you have say 3 of them....I think you get the picture.
This is not to say one is better than the other as people love certain pumps for different applications. This is just the hard facts about consumption of the 2.
Here you go for your own future reference of where your money is going. If you have say 3 of them....I think you get the picture.
| Pan World 200PS | Vectra M1 | |
| 1750gph | 2000gph | |
| 290watt | 80watts | |
| Yearly cost @ 12c/kw $304.85 | Yearly cost @ 12c/kw $84.10 | |
| Yearly Savings for DC Pump $220.75 | ||
| 8 year Savings for DC Pump $1766.00 |
This is not to say one is better than the other as people love certain pumps for different applications. This is just the hard facts about consumption of the 2.
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I think that you likely have those labeled wrong.
In any case, this is a dumb comparison, IMO. If anybody is using a 200PS and a Vetra in the same application, then they made a bad choice... either way. The choice was bad, not the hardware. If you needed to pump up a few stories, then you have to pay the PW price. If you just need a few feet of flow, then it is misunderstood what a PanWorld does and it is like buying a 1 ton diesel dually truck to transport a cordless drill and tape measure to a jobsite.
With the same type of low-spin, low head impeller, a AC pump can do the same thing that a DC pump can do. I have some sicce and tunze pumps that are similar/less wattage than a similar DC pump and move just as much or more water... they are AC and how low RPM, low head impellers. So far, so good.
The good thing is that there are plenty of AC low-head, low RPM pumps on the market if you don't need the failure point of controllers and all of that.
As for other costs that nearly nobody considers... I have lots of acropora and clams of which some are worth $500-1000 an inch. I have never had a pump failure when on vacation, or otherwise. This is well worth $220 a year if I had to spend it.... but I don't.
In any case, this is a dumb comparison, IMO. If anybody is using a 200PS and a Vetra in the same application, then they made a bad choice... either way. The choice was bad, not the hardware. If you needed to pump up a few stories, then you have to pay the PW price. If you just need a few feet of flow, then it is misunderstood what a PanWorld does and it is like buying a 1 ton diesel dually truck to transport a cordless drill and tape measure to a jobsite.
With the same type of low-spin, low head impeller, a AC pump can do the same thing that a DC pump can do. I have some sicce and tunze pumps that are similar/less wattage than a similar DC pump and move just as much or more water... they are AC and how low RPM, low head impellers. So far, so good.
The good thing is that there are plenty of AC low-head, low RPM pumps on the market if you don't need the failure point of controllers and all of that.
As for other costs that nearly nobody considers... I have lots of acropora and clams of which some are worth $500-1000 an inch. I have never had a pump failure when on vacation, or otherwise. This is well worth $220 a year if I had to spend it.... but I don't.
InvictusReef
Active Member
Yeah, you can do it both ways but with the DC pump when you dial it back you don’t worry about generating more heat because you’re clogging the pump. It’s better to dial down the power than it is to force the flow to slow down and have the pump running at maximum capacity IME
From your example. What you are missing is the AC pumps is either on or off. To keep things simple. So if it is 100watt pump and you dial flow down to 50%. No matter what you do to dial back the flow. you can count on basically 100w usage. There are other factors at play here, about strain on motor,etc that are not factored here. Just keeping it simple.
On a DC pump, if you dial it back and its say a 100w pump. For argument sake. if you take it down to 50% for flow. The pump would be using say 50watts. This is just an example, but will bring out allot people ranting and raving about this and that. But its basically that simple.
On a DC pump, if you dial it back and its say a 100w pump. For argument sake. if you take it down to 50% for flow. The pump would be using say 50watts. This is just an example, but will bring out allot people ranting and raving about this and that. But its basically that simple.
DC pumps do not work in all applications. Head pressure is an issue for some, and thus they have to use different pumps. You have to figure out what your needs are and go with what you need. The cold hard facts of watts is what it is and not an argument, but so many people want them to be. There are comparable AC/DC pumps in watt usage, so at that point its up to the consumer has to educate themselves on what they want.
