AC and DC pumps.... not as different as you may think.

[ngvu1]

I like DC pumps since I run the at a lower than the max speed.....longer life.....Less problem....more time to enjoy the hobby or to deal with other issues

Thank you for writing the article!

 

[ksed]

I like DC pumps since I run the at a lower than the max speed.....longer life.....Less problem....more time to enjoy the hobby or to deal with other issues

Thank you for writing the article!

There are more components to go wrong though. Eg controller, power supply.

 

[mcarroll]

longer life.....Less problem

That's one of the less-clear differences to me.

More parts, as @ksed said.

Plus, you have piles and piles of examples of AC pumps that are currently running forever.

Are we going to look 40 years into the future and claim that DC pumps will run "twice forever"?

 

[ksed]

@mcarroll
I am afraid the hobby grade AC pumps eg Eheim and Sicce may go the way of the dodo birds or perhaps very limited.
Even though they are great pumps, they are not readily bought compared to DCs

 

[mcarroll]

Now we are speculating 40 years in the future!

Here's my prediction: As long as the alternative costs more, AC pumps will be more popular.

As it stands, the only alternatives that are "competitive" in your scenario (sales numbers) are the chinese-branded ones. Limited popularity.

By contrast, the brands that seems to be generating all the buzz cost an order of magnitude more than "ordinary" high quality AC pumps.

I don't care how much buzz you see online, $400 return pumps are never going to replace $50 or $90 return pumps.

Return flow isn't even a variable speed application, so the alternative makes no logical sense at all in that situation. (Notice I'm not basing my prediction on this point. People act contrary to their interests all the time. Less-so with money.)

 

[ksed]

Now we are speculating 40 years in the future!

Here's my prediction: As long as the alternative costs more, AC pumps will be more popular.

As it stands, the only alternatives that are "competitive" in your scenario (sales numbers) are the chinese-branded ones. Limited popularity.

By contrast, the brands that seems to be generating all the buzz cost an order of magnitude more than "ordinary" high quality AC pumps.

I don't care how much buzz you see online, $400 return pumps are never going to replace $50 or $90 return pumps.

Return flow isn't even a variable speed application, so the alternative makes no logical sense at all in that situation. (Notice I'm not basing my prediction on this point. People act contrary to their interests all the time. Less-so with money.)

Very true
But I see some many Of those low cost DC brands being brought up on the forums. You don't hear of the othe ACs as much anymore.

 

[mcarroll]

I agree, but that's buzz...

Judging that way you could be excused for thinking all manner of crazy things.

It's the proverbial "if your friends were all jumping off a bridge, does that mean you'd do it too???".

 

[ksed]

I totally agree with you.
Unfortunately a lot of people do follow.

 

[mcarroll]

I know a good number are also just curious because of the buzz on DC pumps in general and are trying it out. It's hard to say how many of those will become repeat buyers once the apparent longevity and heat issues become more known/understood (or resolved).

 

[ksed]

Point well made.

 

[ksed]

Nice to see this topic on the forum.
Let's hope it gets the attention.

 

[Paul B]

I don't really like DC pumps for the reasons stated. They don't last very long. A couple of years won't do it in my tank as most of my AC pumps ran 15 or 20 years with no problems or even maintenance but I have a box filled with DC pumps that croaked in less than a year. I don't care what I pay for a pump, but I want to start it, then not look at it until 2030.
I also see no reason to adjust the speed of a pump. I buy it for the power I need and let it run.

This guy ran continuously for 20 or 30 years. Maybe longer


This little gem ran my skimmer for probably 20 years and I never opened it. It is still running fine.


This thing died in 2 years. I also have a box of these


Of course I also still have this projector that also runs perfectly. For you youngsters, this was the cell phone video machine of the fiftees. (I Phone - 57)

 

[ksed]

I know of those two AC pumps and they are not made in Asia unlike most of the current DC pumps.
I wonder if it has to do with quality control rather than a DC pump.

 

[Brew12]

I know of those two AC pumps and they are not made in Asia unlike most of the current DC pumps.
I wonder if it has to do with quality control rather than a DC pump.

I am guessing that it is a combination of several factors. I agree that all pumps aren't made as well as they used to be. DC pumps have 2 big reliability disadvantages. First is the controller which provides a failure mode AC pumps just don't have. Second is that they run at lower voltage so they have higher current. This means they run hotter, which leads to more thermal expansion. I wouldn't be surprised if DC powerheads are more likely to develop housing cracks than AC powerheads for this reason.

 

[ksed]

What I find interesting is the Abyzz pumps (except the 100w ) run on high voltage as well as R/E pumps.

There are other AC pumps that are fairly quiet eg. Fluval Seas pump (Askoll motor block) , they use a chip imbedded into the epoxy.

 

[mcarroll]

Of course I also still have this projector that also runs perfectly. For you youngsters, this was the cell phone video machine of the fiftees. (I Phone - 57)

The housing and cooling fans on that motor are bigger and burlier than the ones on my 2000's-era air compressor!

 

[mcarroll]

Second is that they run at lower voltage so they have higher current. This means they run hotter,

Interesting. So to summarize...

Higher current makes for a relatively hotter housing.

Higher speeds potentially make a relatively higher concentration of heat at the bearings. A particular problem in the impeller well where circulation can be very limited.

 

[ksed]

This wasn't an issue with small powerhead DC pumps but appear to be more of an issue with larger return pump DCs?
Is this simply due to the fact of higher amps on larger DC return pumps?

 

[mcarroll]

My guess is that more current dictates thicker wires, which are expensive.

 

[Brew12]

This wasn't an issue with small powerhead DC pumps but appear to be more of an issue with larger return pump DCs?
Is this simply due to the fact of higher amps on larger DC return pumps?

A simplified heat loss equation would be W(power losses due to heat)= IxIxR so heat losses due to current are squared.
These issues are all design related or can have design related solutions. I would agree that small powerheads probably don't have much of an issue because of the low power. I would also think return pumps would be less impacted by this because they can be designed with larger frames and better heat dissipation. I think larger DC powerheads would be most susceptible since they have proportionally higher current draw in as small a form factor as possible.

My guess is that more current dictates thicker wires, which are expensive.

More current does dictate thicker wires, but I'm not sure this drives much cost. The copper weight in these pumps is very small and copper wire costs under $6/pound. The difference in copper costs would be marginal compared to the other costs.