DC Pumps? Why isn't anyone using them?

[combatwombat]

Seems they are very popular with aquarium hobbyists. They're low voltage, can be plumbed submersible or external, have variable flow rates, and are super energy efficient. You can find them in a few different brands rated all the way up to about 6,600 GPH.

Why are these not at all popular with the pond community? The main downsides I can see are:

1. The controllers/transformers tend not to be weather rated (probably because only aquarium owners buy them), so you would need to protect them from rain/snow.
2. They don't do well with high head applications. So if you have a tall waterfall or long pipe runs (or both) I think they really under-deliver in those scenarios.

But if you're not dealing with much head and you can protect the electronics, I would think us pond people should be making them fly off the shelves.

But when I do a search on the major pond forums... there's not a lot of discussion about them compared to all the AC pump options.

Why do you think that is?

 

[JRS]

Interesting question. You likely covered most of the reasons. Assuming initial cost must be an issue also, otherwise many would take a chance on a good value despite some drawbacks? Then there is the "used to factor" as a new technology is adopted and spreads if advantages outweigh disadvantages.

 

[jmajid]

Jebao (Jecod), Sicce, Periha come to mind that all manufacture DC pumps with variable speed/flow adjustments.
I have looked into them, not pulled the trigger yet, but do want to look into it I think as the cost to run is much lower compared to my 3/4HP LifeGard Seahorse external pump.

 

[combatwombat]

@jmajid: Yes, the energy savings seem quite substantial, especially with the ability for fine flow adjustment.

I was originally interested in these DC pumps because I know my kid is going to want to get into the pond, and I thought a low voltage DC pump might be a panacea that would allow a submersible pump while still being safe for humans.

But the more I learn about electricity, the less I think that might be true because a GFCI cannot protect a fault on the DC side of the transformer and the bigger pumps (24 - 36v) could still give you a quite a shock if you were submerged.

And the more I learn about how electricity flows through water, the less concerned I am about internal vs external pumps as a fault on an external pump will still transfer electricity into the water as there is a path for it, so you're mostly relying on the GFCI for protection. Externals are still a lot more durable and energy efficient, though.

 

[combatwombat]

Interesting question. You likely covered most of the reasons. Assuming initial cost must be an issue also, otherwise many would take a chance on a good value despite some drawbacks? Then there is the "used to factor" as a new technology is adopted and spreads if advantages outweigh disadvantages.

All the ones I can find are really cheap! Jebao has 5300 gph pump for $225 that runs on 165 watts at highest setting.

 

[combatwombat]

Ok, I just learned something new about DC pumps care of this article from reef2reef.

Biggest takeaway: DC pumps actually operate on AC! The difference between a typical line voltage AC pump and a low voltage DC pump is that the controller for a DC pump (every DC pump requires a controller) converts the AC coming into to DC... so that... it can convert it back to AC at a different frequency. That is how the variable speed is achieved. And it's why the same AC pump is rated for more flow in the US (60 Hz grid) than in Europe (50 Hz grid).

Fascinating!

 

[brokensword]

for comparison's sake, CW, my Danner uses 230w and pumps 4k gph and costs $239 on Amazon. As a spare pump, I also have one from Harbor Freight; 270w , 4K gph, cost = $134. Now, none are variable flow but imo, it's not necessary.

 

[combatwombat]

for comparison's sake, CW, my Danner uses 230w and pumps 4k gph and costs $239 on Amazon. As a spare pump, I also have one from Harbor Freight; 270w , 4K gph, cost = $134. Now, none are variable flow but imo, it's not necessary.

I agree that the variable flow is not necessary. And if it is, there are ball valves for that. I was mostly interested in them for the energy savings and the improved safety of low voltage dc. But now that I know they are actually AC and that low voltage can't (as far as I know) be protected by GFCI, that only leaves us with efficiency.

You can get a 5250 GPH Jebao pump for $200 that will draw 165 watts at its highest setting. That's a pretty big improvement considering 24/7 operation, especially in places with high energy costs.

Seems there is a lot of gripes about how long these pumps tend to last, though. That could quickly eat into the savings if you're comparing a pump you have to replace every few years vs one that will run 20 years without ever even being serviced.

 

[Jhn]

Seems there is a lot of gripes about how long these pumps tend to last, though. That could quickly eat into the savings if you're comparing a pump you have to replace every few years vs one that will run 20 years without ever even being serviced.

I can’t speak for jeboa in relation to pond pumps because I have never used them in this capacity. I have bought 3-4 power heads for use in my reef tanks and they are
complete junk, last a few months at best then crap out. So to me I prefer to do as you suggested and buy a more expensive pump that I know lasts.

 

[combatwombat]

I should put an asterisk next to all my claims about electrical safety as I am learning this stuff in the go and am by no means an expert. I have a good handle on electrical concepts and safety inside a building, but adding electricity to water is new to me.

In general, though, is:

12 vdc in a dry environment is extremely safe. 240vac in a pool of water with no GFCI is extremely unsafe.

And then there are dozens of other scenarios in between those two poles where “safe” and “unsafe”exist on a spectrum and I’m not always confident where each option falls in relation to another.

 

[Doctor mcboy]

Seems they are very popular with aquarium hobbyists. They're low voltage, can be plumbed submersible or external, have variable flow rates, and are super energy efficient. You can find them in a few different brands rated all the way up to about 6,600 GPH.

Why are these not at all popular with the pond community? The main downsides I can see are:

1. The controllers/transformers tend not to be weather rated (probably because only aquarium owners buy them), so you would need to protect them from rain/snow.
2. They don't do well with high head applications. So if you have a tall waterfall or long pipe runs (or both) I think they really under-deliver in those scenarios.

But if you're not dealing with much head and you can protect the electronics, I would think us pond people should be making them fly off the shelves.

But when I do a search on the major pond forums... there's not a lot of discussion about them compared to all the AC pump options.

Why do you think that is?

high voltage pumps are more engery efficient

 

[HARO]

I can’t speak for jeboa in relation to pond pumps because I have never used them in this capacity. I have bought 3-4 power heads for use in my reef tanks and they are
complete junk, last a few months at best then crap out. So to me I prefer to do as you suggested and buy a more expensive pump that I know lasts.

I recently retired (for the second time) from managing the water garden part of a local garden center. I can certainly confirm that the brand you mention is a waste of money. Some of these pumps broke down within HOURS of being put in service, and out of a case of six UV clarifiers, FOUR didn't work, straight out of the box! What's more economical, a $140 pump that must be replaced twice per season, or a $250 pump that runs 10 to 15 years before needing a replacement impeller (about $45)? I should add that I didn't carry the cheaper pumps for long!
John

 

[combatwombat]

I recently retired (for the second time) from managing the water garden part of a local garden center. I can certainly confirm that the brand you mention is a waste of money. Some of these pumps broke down within HOURS of being put in service, and out of a case of six UV clarifiers, FOUR didn't work, straight out of the box! What's more economical, a $140 pump that must be replaced twice per season, or a $250 pump that runs 10 to 15 years before needing a replacement impeller (about $45)? I should add that I didn't carry the cheaper pumps for long!
John

Thanks for confirming that. Seems like most of the brands out there cater to aquarium owners. Have had a hard time finding many that are built for ponds (Aquascape has a few, I guess). And the ones that I could find had dubious user reviews.

Have you had luck with any kind of brushless DC pumps?

high voltage pumps are more engery efficient

I don't think that is correct.

 

[HARO]

Have you had luck with any kind of brushless DC pumps?

Sorry, I've never used one. None of my suppliers even carried them. We sold Laguna pumps for the most part, and I can heartily recommend any of their "Made in Italy" pumps. I have a number of them that have run for 20+ years with no problems.
John

 

[CometKeith]

Sorry, I've never used one. None of my suppliers even carried them. We sold Laguna pumps for the most part, and I can heartily recommend any of their "Made in Italy" pumps. I have a number of them that have run for 20+ years with no problems.
John

I have been happy with Laguna pumps over the years as well. At any one time I have 3 running all the time even through most of the winter...One for my bog and two waterfall pumps splashing water. They have low energy consumption and are reliable. I even had ice freeze in one of them a few years ago in the middle of the winter and was able to restart it in the spring with no problems.