Hydor Koralia Super-Mod
- Thread starter kroe
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vt4lifecuf
New member
thanks for the tips
After permanently attaching the Octura 1240 prop to the MJ impleller drive, the modded K4 is now consistently pumping out more flow than a modded 6025. It now draws 17W and by my guess pumping 1,600gph.
The modded front cap caused some vibration noise since it was difficult to center it perfectly. Guess the stock cover is the only way to go and we just have to live with the bigger size.
The only concern now is the fact the K4 motor is rated 12W, the long term prospect of over-driving it at 17W is anyone's guess. So any experts here want to speculate on that?
The modded front cap caused some vibration noise since it was difficult to center it perfectly. Guess the stock cover is the only way to go and we just have to live with the bigger size.
The only concern now is the fact the K4 motor is rated 12W, the long term prospect of over-driving it at 17W is anyone's guess. So any experts here want to speculate on that?
Altpers0na-old
Reefer
its going to fail sooner than it should.... your adding nearly half again the watts it should use... more heat , more stress, less pump life.
but how much less... thats anyones guess...
but how much less... thats anyones guess...
chem-e
Active member
I ran the K4 with the Dumas 3004 and it was just too much flow for my 3 ft wide tank. I have a couple of Octura 1435 props on order, so hopefully, these will be more in line with what I need.
For those of you looking for a good amount of flow at a decent price, the K4 w/ Dumas 3004 is the way to go. The only change is the prop and magnet, so it looks stock and it also has a magnet mount. It's a little bigger than the Nanostream, but it moves a lot of water. I don't know about power draw because I don't have a meter.
For those of you looking for a good amount of flow at a decent price, the K4 w/ Dumas 3004 is the way to go. The only change is the prop and magnet, so it looks stock and it also has a magnet mount. It's a little bigger than the Nanostream, but it moves a lot of water. I don't know about power draw because I don't have a meter.
You can just trim the prop more for less flow. Any of the props mentioned above will be too big for the K4 motor to handle, I have tried all of them (Dumas 2004, Oct 1435, 1440 and 1240), they all needed trimmed back, so all ended up the same size after the trimming.
The Octura 1240 prop fits the MJ impeller perfectly, no need of any sanding or cutting to fit, I didn't even have to use glue, it is just that nice a fit. And I even like the yellow better.
OK one small correction, I did have to sand the little bump on the impeller shaft in order to press the prop into it. The bump is visible in the prop/impeller picture above, it is right below the yellow prop. After the bump was sanded narrower, the 1240 prop pressed right into it and made a very good and tight fit so no glue was even necessary.
The Octura 1240 prop fits the MJ impeller perfectly, no need of any sanding or cutting to fit, I didn't even have to use glue, it is just that nice a fit. And I even like the yellow better.
OK one small correction, I did have to sand the little bump on the impeller shaft in order to press the prop into it. The bump is visible in the prop/impeller picture above, it is right below the yellow prop. After the bump was sanded narrower, the 1240 prop pressed right into it and made a very good and tight fit so no glue was even necessary.
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jacmyoung: I love how you have worked out a polished mod for these pumps, but I don't think that wattage * 100 measure is even close.
These presumably spin at the same RPM as MJ mods (no numbers, but based on same prop performance they must). That would put a dumas 3004 unmodified close to 2000 gph.
medic: good work getting the 3004 on there, I was waiting for someone to try one of these low pitch but large props! They seem perfect for the K4 given the large shroud. What did you use for a magnet, the MJ 1200 mag?
These presumably spin at the same RPM as MJ mods (no numbers, but based on same prop performance they must). That would put a dumas 3004 unmodified close to 2000 gph.
medic: good work getting the 3004 on there, I was waiting for someone to try one of these low pitch but large props! They seem perfect for the K4 given the large shroud. What did you use for a magnet, the MJ 1200 mag?
medic29
Premium Member
Yep, plus I still had some carbon fiber tubing lying around so I used it and was able to cut it to length where the magnet would come out of the motor when the prop was turning the wrong direction, the pop back in and start turning in the right direction. Works pretty good.
Interesting I had to trim back my Dumas 3004 quite a bit for it to work with my K4 motor. What was the watt rating on that MJMod with untrimmed D3004?
I do see D3004 is very different than most all other props we use, in that it has a much bigger diameter but very low pitch. Maybe such design is more efficient?
I do see D3004 is very different than most all other props we use, in that it has a much bigger diameter but very low pitch. Maybe such design is more efficient?
gpodio
Premium Member
If my knowledge of AC induction motors (from other hobbies) is valid here then I don't believe they all spin at the same rate. The magnetic field rotates at the source frequency (AKA the synchronous speed) but the rotors always spin at a lower rate. The difference is called the "slip %". The more resistance the propeller gives the slower it will spin... The only thing that is the same between pumps is the synchronous speed which is set by the AC frequency.
So finding the best propeller for the tourque this motor can generate is not as easy as it appears, there's a lot to it. At times a smaller prop with a higher pitch will generate more flow than a larger prop with less pitch... or one with an extra blade...
If I'm not mistaken the larger the slip the less tourque the propeller will have, that will play a big role in determining the best propeller.
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Edit: Actually, I believe it is more correct to say that as slip rises from 0%, rotor tourque actually increases but beyond a certain slip % it will start to drop considerably. I think I got it right this time as 0% slip woud mean 0 tourque as the rotor would be under no load.
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Again, knowledge from another hobby but I do believe AC motors are all pretty much the same in these aspects.
One question, I have a standard 180g All-Glass tank, is the magnetic mount on the #4 model strong enough to rely on? Where did I read someone had theirs slip down on 1/2" glass??
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It was me, the pump stayed but was close, and the motor had to be at the under side, if the suction cups wear out (we know they always do), the pump will slide.
BTW, thanks for your insight. I think you are right. When I modded with different props, I noticed when the motor was pushed to the limit, the flow reduced while the watt draw increased, must be slipping badly. But at certain working range the slipping effect has to be minimal, else the DC pumps can't have multiple speed settings. Although I think DC motors work differently than the AC ones.
BTW I needed a few K4 parts had a little chat with Bruce at Hydor, a very nice guy. He said Hydor is coming out with a more powerful K pump, probably the same size as K4 but more flow. They also are working hard on controllers for the K pumps.
BTW, my flow=100Xwatt math was not totally pulled out of a hat. I looked at all the AC stream pumps and their factory specs and came up with this simple rule of thumb, just to offer some clue if you can not or don't want to test the flow. Variables such as mentioned above, and others such as how big the opening and how restrictive are the slits too can influence the flow.
BTW, thanks for your insight. I think you are right. When I modded with different props, I noticed when the motor was pushed to the limit, the flow reduced while the watt draw increased, must be slipping badly. But at certain working range the slipping effect has to be minimal, else the DC pumps can't have multiple speed settings. Although I think DC motors work differently than the AC ones.
BTW I needed a few K4 parts had a little chat with Bruce at Hydor, a very nice guy. He said Hydor is coming out with a more powerful K pump, probably the same size as K4 but more flow. They also are working hard on controllers for the K pumps.
BTW, my flow=100Xwatt math was not totally pulled out of a hat. I looked at all the AC stream pumps and their factory specs and came up with this simple rule of thumb, just to offer some clue if you can not or don't want to test the flow. Variables such as mentioned above, and others such as how big the opening and how restrictive are the slits too can influence the flow.
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gpodio
Premium Member
So the magnetic mount itself still relies on the suction cups for added support? If it's not 100% solid on the magnetic mount alone I'm getting another Seio, my first one without the 90 degree diverter works very well...
Yeah DC motors vary greatly in speed and you can easily modify their speed by changing voltage, DC motors can slip till they're black and blue in the face and still have good tourque. This is why DC motors have good starting tourque. You'll always have some slip under load in your pump, it's finding that perfect balance between slip, tourque and prop efficiency. It can be surprising at times what prop gives the best results on a particular motor.
Cool! I have worked with AC motor controllers but the ones I have are not suited for continuous running, they get too hot for that.
You'll likely find that as soon as you modify a single item such as the prop, it will change current drawn, slip and volume pushed, I am not convinced that formula would remain accurate if any one of these things changed. If you could measure watts AND RPM, perhaps one could guess the flow based on prop specs. It isn't easy to measure volume pushed in a such a large cone, perhaps if you "hang" a cork from a string tied to a rock you could compare the angle the string and cork tilt to when placed in front of the pump at a certain distance. At least you'd know which prop pushes more water, the actual flow rate would still be difficult to guess though.
One of these days I'll find the time to play with these things again, I have many props to play with from the old RC boat racing days..
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