View Full Version : Had a dream about pumps last night....


atreyu917
07-09-2009, 7:19 AM
....haha. Seems funny, and it was, but it got me thinking.... Do pumps really ever give you signs when they begin to fail? How long is their life generally? I got a mag 9.5 used, and it's been running great for about 5 months now.

I'm just wondering if I should buy another and have it handy just in case my 9.5 ever goes bad and stops working.

And maybe now I'm just being paranoid, but it seems to be making a pulsing noise I haven't noticed before. haha.

DrNecropolis
07-09-2009, 7:33 AM
Mine never had.. the only sign you get is "Why is the water level in the tank a foot low" then its a nightmare on friday street

radha
07-09-2009, 9:12 AM
Ha ha, I had a dream that I got an RBTA (this was about two weeks ago, and it was the day before I got my GBTA) and I didn't acclimate it, and then I got super scared it was gonna bleach. Later on in the dream, I dreamt that I got a fish that was a mix of a candy basslet and six line wrasse. It was very strange... lol. But I always have the weirdest dreams!!

wbrown
07-09-2009, 9:35 AM
the only moving part in a mag pump is the impeller, so you should be good for a long, long time.

atreyu917
07-09-2009, 10:16 AM
Ok good hahaa cause I am not worried i'll come home to a huge mess and my fish will be dead.

Acroholic
07-09-2009, 10:38 AM
If you want to you can keep a spare impeller like brown said. They only cost about $15 I think.

I have a little giant 3mdqsc external that I bought used about 2.5 years ago for $22 that is still going strong on my 265 gallon FW tank.

But over the years I have found that it is a good idea to keep a spare pump around for emergencies. Not necessarily a really powerful one, just one to keep circulation going thru the sump in case your own pump dies.

atreyu917
07-09-2009, 10:39 AM
I'll definitely keep an eye out for a smaller pump, just in case. I know I'll kick myself if I don't prepare for an emergency.

wbrown
07-09-2009, 10:44 AM
I do keep a spare pump on my water mixing barrel just in case.. the same model and all, just not in constant use.
I have others as well IF the need arises, but having one spare impeller should suffice.
You'd notice if the return pump failed, aiming a powerhead at the water surface should keep livestock alive until you repair or replace though.

ares
07-09-2009, 10:51 AM
Ive had external pumps fail, but never a mag pump... external just... quit one day. I tried everything to fix it. it would run dry if I flicked the impellor. it would run wet if I flicked it, but only for a few minutes, then itd eventually stop again. manufacturer said eventually it would just lose power till it couldnt keep the momentum anymore :/

mags are all still running strong though.

I dream about my tank too... and they are messed up dreams... I imagine an anemone... and it does like... a griswalds christmas turkey thing, where it is dry and cracks open somehow... its not a healthy dream.

atreyu917
07-09-2009, 11:08 AM
I always dream about work and my tank and that's about it haha

acroporas
07-10-2009, 9:50 AM
....haha. Seems funny, and it was, but it got me thinking.... Do pumps really ever give you signs when they begin to fail? How long is their life generally? I got a mag 9.5 used, and it's been running great for about 5 months now.

I'm just wondering if I should buy another and have it handy just in case my 9.5 ever goes bad and stops working.


Mag drive pumps last FOREVER. I have several that have been running for over 10 years.

Rbredding
07-10-2009, 10:24 AM
^^ THAT BEING SAID....


why have only one when you can have a perfectly good "backup" on the ready...
mag9.5 isn't a tough pump to find, but if you're running something more exotic (or something more powerful) then it would be crazy of you not to keep an extra on hand..

you'll probably be fine.. mag(netic) pumps are amazing... the motor runs a cylindrical magnet around in a circle (like looking into a dryer that's running) and the impeller is completely enclosed in a housing (usually that can be disassembled for repair) that slips down inside the cylindrical magnet..
the impeller assembly is also North/South charged so that as the magnet spins around the assembly, the impeller within the impeller assembly rotates.. (picture moving a fork across a table with a magnet from underneath)..

low friction, very few moving parts, motor is completely isolated from contact with water... WIN, WIN, WIN.. !

atreyu917
07-10-2009, 10:32 AM
Wow, that's awesome. I really had no idea they worked like that, thanks for the mini lesson!!!

Rbredding
07-10-2009, 10:47 AM
Wow, that's awesome. I really had no idea they worked like that, thanks for the mini lesson!!!


I didn't either... until I took apart my BlueLine 40HDX to figure out why it had seized up... (it was broken down wet then stored and the saltwater inside evaporated causing the crystals to act like glue and everything stuck together)...

the motor would spin, but nothing would move in the impeller housing..

once I took THAT apart and figured out what the problem was (and then cleaned the unit completely)... it spins like a top now... (without the wind down and fall over that a top suffers from)..

acroporas
07-10-2009, 12:16 PM
mag(netic) pumps are amazing... the motor runs a cylindrical magnet around in a circle (like looking into a dryer that's running) and the impeller is completely enclosed in a housing (usually that can be disassembled for repair) that slips down inside the cylindrical magnet..
the impeller assembly is also North/South charged so that as the magnet spins around the assembly, the impeller within the impeller assembly rotates.. (picture moving a fork across a table with a magnet from underneath)..

low friction, very few moving parts, motor is completely isolated from contact with water... WIN, WIN, WIN.. !

That is not completely accurate. While I am sure that there are pumps out there that work like that, that is not how most submersible pumps work. Submersible pumps are even more simple.

There is only 1 moving part in the pump: the impeller. As Rbredding described the impeller is a magnet.

But inside the sealed plastic container, is nothing but a coil of wire. There is nothing in side the "motor" that can break. The only way those pumps can "break" is if water gets in causing a short circuit. The most common cause of leakage, is that you let it run dry for a long time, it gets too hot, and the plastic case melts.

Here is how a submersible pump works.

- The coil of wire inside the plastic housing creates a magnetic field when electricity flows though it.
- The magnet on the impeller will align with the magnetic field created by the coil.
- Our electricity is call AC - alternating current. That means that the current in the wire, alternates direction frequently. 60 times per second to be exact. Each time the electricity changes direction, the polarity of the magnetic field created by the coil reverses.
- In reaction to the change in the magnetic field, the impeller will rotate 180degrees to match.
- The current keeps reversing it self, the magnet keeps rotating to to keep alignment, although the magnet could spin either direction to realign, but because of momentum, once it gets started spinning in one direction it keeps spinning in that direction. And thus the impeller spins.

Some interesting side effects of the way these pumps work.

- Since the frequency of the AC is fixed. All magnetic pumps' impellers spin at the same speed. The difference between a pump that moves a little water and a pump that moves a lot of water is just the size of the impeller.

- The only way to change the speed is to change the frequency of the AC and the strength of the magnetic field. It is very difficult to do those two things. That is why there are no AC pumps that are controllable. (compared to DC pumps that only need to have the voltage changed(which is very easy) to control them)

- The pump does not "tell" the impeller which way to spin, when it realigns itself to the magnetic field. Thus direction the impeller spins is completely random. One time it might spin to the right, the next time it might spin to the left.

Rbredding
07-10-2009, 12:23 PM
...interesting...

I figured the submersible pumps to be different, just didn't know to what degree...


the theory is still the same.. .using a magnetic field to move an impeller, without a physical connection to the motor...



question though...

since there is no shaft connection to "bind" the motor (which is what usually causes the conventional motor to overheat and fail)...
how will running dry or binding a propeller cause a motor to overheat?

acroporas
07-10-2009, 1:06 PM
...interesting...

I figured the submersible pumps to be different, just didn't know to what degree...


the theory is still the same.. .using a magnetic field to move an impeller, without a physical connection to the motor...



question though...

since there is no shaft connection to "bind" the motor (which is what usually causes the conventional motor to overheat and fail)...
how will running dry or binding a propeller cause a motor to overheat?

External pumps are air cooled. The shaft has fan blades that blow air on the coil to keep it cool. If the shaft stops spinning, the fan stops blowing, and the pump over heats.

Internal pumps are water cooled. Water conducts heat MUCH better than air, so no fans are needed - just the fact that they are submerged in water, will keep it cool, even if the impeller stops spinning or water stops flowing, a high quality submersible pump like a magdrive will not over-heat while submerged. (cheap ones like the infamous rios will though)

But when you take it out of the water, and run it dry, even if the impeller is still spinning the pump will over heat because air can not conduct away enough heat.

Internal/external pumps, (such as a mag-drive) when being used as an external pump, it is cooled by the water in the impeller chamber. So if the water stops flowing though the impeller chamber (either because of a broken impeller or because of a clogged intake) the pump can over heat.

Rbredding
07-10-2009, 5:10 PM
my mag drive external pump.... no shaft, no "fan" blades to cool the motor... what cools it? (other than vents in the housing - there's no mechanical way that air is pushed over the motor) not that it runs very hot to begin with, I'm just curious..

acroporas
07-10-2009, 5:19 PM
my mag drive external pump.... no shaft, no "fan" blades to cool the motor... what cools it? (other than vents in the housing - there's no mechanical way that air is pushed over the motor) not that it runs very hot to begin with, I'm just curious..
The water flowing though the impeller chamber cools the motor passively.

tjherman
07-10-2009, 10:44 PM
Wow, this turned into a great lesson on the mechanics of pumps. Sounds like the magnetic pumps are real beasts.