Why is my MJ1200 with SureFlow mod doing this?

[Myka]

Originally Posted by mike31154

It is possible that the propeller may be fitted on to the shaft the wrong way around though.

Mike, you are BRILLIANT!!

The prop when it spins one way rams right into the tab, but if it goes the other way because the prop is slanted if it hits the tab it just slides up it.

I think it's actually messed up and spinning the wrong way because it took some serious efforts to get the propeller off which makes me think that no one turned it around. BUT, it worked!!! Well, it's been running for about 5 mins and hasn't messed up yet. So...fingers crossed. I'll see how it runs, but it's doing ok now. Has a bit of a vibrating hum to it though...but I think once my MH setup gets here and the fans are going I wouldn't hear the hum of this powerhead. Every once in awhile it puts out a fairly loud buzz. This is my first try at these SureFlow kits...so far, thumbs down. Noisy! (even at the best of times...maybe better when they are new though)

I didn't get the smaller black propeller, which I am a bit disappointed because I wanted to put the smaller one in a 900 and use the bigger one in the 1200. Extra greedy.

[Delphinus]

Glad you've figured it out but boy that doesn't make sense. The powerhead can spin either way, so if the prop was upside down it just needs to spin the other direction if it's going backwards at startup.

Oh well, apparently I'll just hurt myself if I think about it any longer ... so I'm not going to. Either way I'm glad you figured it out. But yeah, these kits are good for giving you flow in a hurry without spending gobs of cash, but that's about it. Like anything I guess ya gets what you pays for.

[mike31154]

Great, glad it's working for you... so far. Dunno about brilliant though, I'm not filthy rich, call it logical, although I don't have pointy ears, har har. Probably all the good training for my tech. career fixing aircraft instrument electrical systems. And yes, I did have the opportunity to work on some old prop jobs there, as well as the jets.

It was a long shot, but lucky I guess. I've never seen the Maxi Jet mod up close, but I tried to mod a couple of AquaClear power heads with propellers I purchased at hobby shops. The smaller ones seemed to work better, fkshiu's theory on mass of the larger prop has merit, I'm sure. When I fitted a prop to an AquaClear 802 and finally got it to spin in the right direction, the thing went nuts! So much power I could have emptied my tank in a few minutes with the water slopping over the rim!

Now with respect to the vibrating hum, I suspect that may be due to a slight imbalance and the fact that you're working with a longer shaft than the original design of the Maxi Jet. A minor misalignment of either the prop or the shaft will contribute to this excess vibration & noise. You almost need a secondary bearing farther up the shaft to minimize or eliminate any misalignment or flex. My fellow mechanical type techs had some pretty sophisticated equipment to balance props on aircraft & track rotors on helicopters. It doesn't take much to make equipment rotating at high speed self destruct. Even a few grams of difference can be huge and alignment is crucial as well. If it gets out of hand, or before it does, it might be worthwhile to ensure the prop is fitted as straight as possible on the shaft and that the shaft itself is not off at a slight angle. Then again, every time the prop hits the tab, it may mess up any effort you make to keep things straight.

Great mods for the money, but I'm glad I have my VorTech, it's designed with a prop in the first place and has a controllable DC motor, too bad the price is so hard to take. Wonder how the previous owner of the Maxi Jet dealt with the issue you experienced??

Live long and prosper.

[Myka]

Ya, I don't understand why it's spinning backwards, and ALWAYS spins backwards, not just on startup. I can't even get it to spin the right way if I stick my finger in it (which hurts btw).

The only reason I bought it is because I was in need of some cheap water movement for now until I buy a Wavebox and/or VorTech or...?

Oh, and no it's not on a wavemaker.

[mike31154]

Ok, now you've got me confused. Always spins backwards? So it is currently drawing water through the front and pushing it out the sides/cage? I can't conceive of how that would work without the prop continually hitting the tab since the shaft & prop would be moving towards the front of the cage & tab? Where exactly is this tab located, at the front end of the cage, perimeter?? Should be a 50/50 chance that the thing will spin in either direction at start up and half the time not even hit the tab on start up. Just too difficult to visualize what you're describing.

[Delphinus]

Clearly, she's plugged it in upsidedown. I'll refrain some making any blonde references now.

[mike31154]

That's it, her stunning good looks are making the electrons run backwards.

[Myka]

Well, it was freakin difficult to get that propeller off the shaft and turn it around, so I'm assuming that no one took it off and put it back on backwards, so that makes me think that the propeller is spinning in the opposite way that is was intended. If you look at the propeller from the front it is spinning counter-clockwise. It spins the same way every time I plug it in.

Oh, and the frickin thing is going to be banned to salt mixing as soon as I find a replacement. It is obnoxiously loud. Grr.