dc pump, are they reliable? does it save you much on electricty?

[G.T]

I have used DC pumps for the last 18 months. All Jebao mainly dc6000 and 9000, both work hard and have never missed a beat. Maintenance is performed every 2 months or so, just to clean impellors like any other pump. Cheaper to run, and super quiet.

 

[maximo]

The check valve bulkreef recommended can be easily disconnected so it can be cleaned(not to mention replaced) at the same time as my routine pump cleanings; simply unscrew both fittings and give the valve a vinegar bath and replace. Im not using the check valve to restrict water from draining as it will still come down the drain side anyway; just to prevent the pump from back spinning and hard restarting during real quick power outages. Bulk reef supply did warn me of possible leaking over time that's why they recommended using the spears valve they sell for ease of maintenance. I feel that I may have had the pump overworked for the entire time it was in use as it always seemed to run quite hot (10' climb). Overheating would cause bearing failure, if saltwater was getting inside the motor there would be more of an electrical problem then just simply bearing noise. You would think a pump rated for such use would at least have some cooling fan to protect itself. Im not trying to bash pan world pumps, I just feel they should be used less than what they are actually rated for. I appreciate your concern on the check valve but they do more good than bad. Here is an article that explains bearing failure due to hard starts and restarts. http://franklinaid.com/2012/03/14/why-motors-fail-part-2/

^ that's very odd. I wonder if the pump either had defective bearings, or if the bearings somehow got contaminated with saltwater leading to an early death? Definitely not typical.

I have no idea what they are talking about in terms of the check valve and back spinning. I like BRS and generally agree with their advice, but I don't know about this one. I can't see any way in which spinning backwards would be harmful to ball bearings, and it seems like a stretch that it would harm the impeller. Regardless, my caution about check valves in saltwater is because they are inherently un-reliable in saltwater due to the tendency for things to grow and or accumulate on the sealing surfaces.

Whatever the case, bearing noise is bearing noise and when you hear it they are done or at least on the way out. Sorry you had a disappointing experience with a usually reliable pump.

 

[dz6t]

Jebao actually made many so called named brand pumps. Just like a lot of equipment in this hobby, you may not get what you paid for.


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[JohnK]

The check valve bulkreef recommended can be easily disconnected so it can be cleaned(not to mention replaced) at the same time as my routine pump cleanings; simply unscrew both fittings and give the valve a vinegar bath and replace. Im not using the check valve to restrict water from draining as it will still come down the drain side anyway; just to prevent the pump from back spinning and hard restarting during real quick power outages. Bulk reef supply did warn me of possible leaking over time that's why they recommended using the spears valve they sell for ease of maintenance. I feel that I may have had the pump overworked for the entire time it was in use as it always seemed to run quite hot (10' climb). Overheating would cause bearing failure, if saltwater was getting inside the motor there would be more of an electrical problem then just simply bearing noise. You would think a pump rated for such use would at least have some cooling fan to protect itself. Im not trying to bash pan world pumps, I just feel they should be used less than what they are actually rated for. I appreciate your concern on the check valve but they do more good than bad. Here is an article that explains bearing failure due to hard starts and restarts. http://franklinaid.com/2012/03/14/why-motors-fail-part-2/

No cooling fan? The larger ones have them on the back end of the motor, I'm surprised to hear that the 40 doesn't have one. The comprable sized iwaki has a fan.

I agree that very bad things would happen if saltwater was getting into the motor itself, I was just thinking out loud about why bearings would fail so prematurely.

Interesting link about how pumps fail. I do wonder how much of that carries over to magnetic drive pumps since the article seems to be focused on direct drive pumps, but regardless it's an interesting read.

 

[this is me]

Not to derail the thread but why would you want a check valve on your return. Design your sump so that it's big enough to handle the back flow from the display in an event of a power outage is the best practical way to avoid overflowing sump issue. Why put a check valve and have to clean it?

I'm waiting for the the flowrate vs. head pressure vs. wattage chart from Ecotech and I'll be in for two of the M1. It's rated as 2000gph with 21.6' of head pressure. It only have to pump up 4' in my system.

 

[Jim Tansey]

Maximo

You say you are not using the check valve to stop water from draining back through the pump but to prevent back spinning, if the draining water is not causing the backspin what is? I can't help but to believe someone at BRS gave you some misinformation regarding back spinning, unless I'm way off base in my understanding of the issue I can't see how a little backspin from the drain could possibly hurt the pump.

Jim

Jim

 

[JohnK]

^ He said earlier in the thread that bulk reef supply advised him to use the check valve to prevent back flow from spinning the impeller backwards in the event of a power outage. I've never heard of that being a problem or concern as long as I've been in the hobby, but then again it wouldn't be the first time that I was the last one to get the memo on something.

*Note, Jim and I posted at the same time*

 

[this is me]

I highly doubt the flow rate from back siphoning of the return can cause the motor to spin backward especially enough motion of the motor to cause damage. But I could be wrong. Must be a a pretty crappy motor and pump design.

 

[JohnK]

That's the thing, every pan world pump I have encountered was built like a mack truck.

 

[maximo]

Think of it like this, if the power cuts out for 4 seconds the pump will still have water flowing through it in the reverse direction. After 4 seconds the power comes back on and the pump has an extremely hard restart. Inside the pump there are two bearings that look like roller blade or skateboard bearings. When the pump hard starts the propeller shaft will thrust to a side causing strain on the bearings. Being that the pump is already overheated the bearings can warp easily during an extreme restart such as trying to redirect a falling 10' water column. Even if the check valve were to leak slightly it would still drastically reduce the strain on the pump. Spinning the pump in a reverse direction has no ill effect on it. The damage results in the hard restarts redirecting a falling water column. I actually observed the pump restart during the quick power outage when it started making an extremely loud hum. It's the outer bearing on the shaft I've been tossing the idea around of trying to get a replacement and pressing it on. I originally decided on this pump due to all the praise and proven longevity they have. Btw my iwaki md 40 rxt does have a cooling fan.


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[Jim Tansey]

I don't buy it the motor as has been pointed out is not directly coupled to the impeller but rotates indirectly by the way of magnetic interface thus greatly limiting the available torque to destroy the bearings.

Jim

 

[zkilloy]

I Thought that small aquarium/pond/fountain pumps generally have one bearing on the end of the impeller and this is usually ceramic and not a roller bearing, the magnet side just floats. Is that not correct? The motor windings are encapsulated and the shouldnt need to move. I'm not 100% sure but I thought this was how it worked.

Plus, most DC aquarium pumps with a controller have a programmed soft start..

 

[JohnK]

I Thought that small aquarium/pond/fountain pumps generally have one bearing on the end of the impeller and this is usually ceramic and not a roller bearing, the magnet side just floats. Is that not correct? The motor windings are encapsulated and the shouldnt need to move. I'm not 100% sure but I thought this was how it worked.

Plus, most DC aquarium pumps with a controller have a programmed soft start..

We're talking about a more heavy duty external pump here. It has ball bearings in the motor housing. The impeller (most likely, I don't have this exact pump in my hands) spins on a ceramic shaft with a bushing on one or both ends. The motor is connected to a magnetic ring that spins around the sealed impeller housing. The motor has a corresponding magnet, and the impeller is moved by that magnetic interface.

This is the pump in question;
http://www.bulkreefsupply.com/pan-world-40px.html

And yes, I'm with Jim, still trying to understand how this is an issue considering that it's magnetic drive. I can see the concern with a direct drive pump, but direct drive pumps are virtually unheard of in the hobby. I'm not saying it's wrong, just saying that I still don't get it