# Hydor Koralia Running Backwards



## Rialb30 (Feb 25, 2010)

My one year old evolution 750 has started running backwards. If I unplug it, it starts normally then the next day I find its running backwards again. I have tried disassembling the pump and cleaning, but that didn't fix the problem.
Has anyone else experienced this problem? Does anyone have a possible solution?


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## Sub-Mariner (Dec 7, 2011)

I have 2 Evo 750s and thankfully I dont have that problem. *** read about that happening with other powerheads / circulators and the way to fix it was to unplug it like you did. Thats weird yours will run the correct way after unplugging it but will switch directions later on.

I could be completely wrong and I cant remember if this was regarding the Evos or not but I think theres a little rubber piece in the front of the fan housing....is your rubber piece there? Some said if the rubber piece is missing it could cause the propeller to change rotation...again I cant remember if that was about the Evos or not and I might be wrong, thats been known to happen. :lol:










Also check out post #13 in this thread: http://www.reefcentral.com/forums/showt ... ?t=1817809


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## PfunMo (Jul 30, 2009)

No solution but I found my new model Maxi-jets are doing the same. I was hoping for a solution from Marineland but never received it. In discussions here, I got some help. 
I'm guessing your pump has some system like mine. It takes a bit of understanding of what the magnet and coil do. The magnet has poles (N&S?). When the power is plugged in the AC current in the coil may be positive or negative depending on the split second timing. If it is the correct polarity to pull the section of magnet that it meets, the impeller will spin correctly. If it happens to be the wrong polarity, the impeller may be pushed rather than pulled. In this case most mag motors have some type of stop which the impeller bumps into for the split second it takes for the 60 cycle to pass on to the corrrect polarity and make the impeller turn the correct way.

I'm guessing that your motor may start correctly sometimes but not other depending on your luck of timing when it is powered up. I suggest looking for some type of stop on the frame or the impeller than should stop the impeller from turning the wrong direction. My case was that the impeller was not sliding on the shaft as it should and was not engaging and releasing as it was designed. You might look for this on your motor.

The problem








The real cause









Mine had spun the wrong way so long that the rubber at the tip was burred off and no longer held the stop as it should. Seems a bad design but all mag drives seem to have some form of this stop to force the impeller to stop and then turn the correct way.


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## bbortko (Nov 20, 2011)

I had the same problem and it was due to the piece sub mariner mentioned.


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## PfunMo (Jul 30, 2009)

Once I thought about how the timing of the AC and the location of the impeller magnet had to work together, a stop of some sort made sense. The tricky part of stopping the impeller when it starts up in the wrong direction took longer for me to see. When the prop starts it acts just like the prop on a boat and presses forward or back. That provides a way to have a stop for killing the movement in the wrong direction but letting it pass when running in the correct direction. The prop is designed to shift forward or backward slightly to clear the stop when running in the correct direction. I can see there might be times when the prop doesn't slide easily on the shaft and that would keep the stop from doing it's job. In my case the parts on the shaft were not pressed far enough together to let the prop clear the notch so it failed. Simple fix once I found the problem but by that time the prop had been turning in the wrong direction long enough to wear the rubber bushing so that it no longer works as a stop.


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## Rialb30 (Feb 25, 2010)

Thank you for all of your replies! With your help I have a much better understanding of how this pump works
I think I have been able to diagnose what is going on with my pump. On closer inspection I found that one of my little saboteurs had evidently spit sand in the pump and damaged the shaft where it contacts the bushing causing the shaft to bind and momentarily stop. Then when it would restart it would occasionally start in the reverse direction, because I also found the little rubber bumper that sub-mariner mentioned had fallen out. It fits so loose that it was easy for it to fall out once the pump had stopped. Cleaning up the shaft and adding a little bit of Teflon tape to the bumper before inserting it has gotten it running normally again. 
Though even as we speak I am sure that my little mbuna terrorists are plotting there next attack. :lol:


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## PfunMo (Jul 30, 2009)

Have you seen the show about Nemo? I think they must all be cichlids planning the next breakout! My grandkids laughed for hours and came to tell me about my fish wanting out. They know about my problems with fish.


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## Sub-Mariner (Dec 7, 2011)

PfunMo said:


> Have you seen the show about Nemo? I think they must all be cichlids planning the next breakout! My grandkids laughed for hours and came to tell me about my fish wanting out. They know about my problems with fish.


Im so sick of that movie!! :x Everytime I take my daughter to ITZ and we eat in their movie room, theyre playing that movie! I hate it but my daughter still loves it, so nevermind I love it too!


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## Rialb30 (Feb 25, 2010)

I just received an email from Hydor indicating that they are sending out a new front cover for my evolution power head. It's this type of customer service that will retain me as a loyal customer for years to come. :thumb:


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## PfunMo (Jul 30, 2009)

Other than running into this small problem, how do you feel about the powerhead when it is running the correct direction? Does is make a noticable hum when the room is quiet?


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## Sub-Mariner (Dec 7, 2011)

Rialb30 said:


> I just received an email from Hydor indicating that they are sending out a new front cover for my evolution power head. It's this type of customer service that will retain me as a loyal customer for years to come. :thumb:


WOW, in 2011 thats some GREAT customer service right there! I bought a 1400 that arrived today, cant wait to fire that bad boy up. 8)



PfunMo said:


> Other than running into this small problem, how do you feel about the powerhead when it is running the correct direction? Does is make a noticable hum when the room is quiet?


I cant speak for Rialb30s Evos but my 2-750s are very quiet, no hum what so ever you cant even tell theyre running. Cant say the same for my Maxi-jets.


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## Rialb30 (Feb 25, 2010)

My evolution 750 is also very quite. In fact I have been watching mine closely for the last few days and its been hard to tell if its running or not. The only real sign that its NOT running is when the poo starts to settle on the bottom.


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## PfunMo (Jul 30, 2009)

As I've had trouble with the Maxi-jet props, I switched to the impellers and am using them as just powerheads but now I find they make a distinct hum which bothers my wife. I'm finding no way to get rid of the hum. The impellers are new and the body as clean as I can get it but I've tried mounting it on all kinds of things and can't get rid of the hum. Looking for the next great item to "need" ! :lol: 
The question is like always. Which is the better buy. A Maxi-jet pumping 750 GPH for $20 but can't be used that way and makes noise or Koralia 750 pumping the same amount but costing $45?

Thanks for the input.


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## Narwhal72 (Sep 26, 2006)

Why not try a different brand of pump? What about an Aqueon Circulation pump?

Andy


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## PfunMo (Jul 30, 2009)

Aqueon is cheaper but I've had less than stellar performance from heaters and stands from them and so I have not looked at their pumps as a good choice for quiet. I have not tried them, though.


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## Narwhal72 (Sep 26, 2006)

You should give them a shot. They are made by the same Italian company that made the original Maxi Jets (before Marineland took them to China).

Of course they also make the Aqueon heaters too.

Andy


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