Anyone using modded MJ as return pumps?

[Inflames]

Seems to me theres a lot of potential now with the mj mods to be used as more than just powerheads. Wouldnt be that hard to connect a return line and throw one in a sump. Granted they wont push probably higher than 3' even modded. A cheap return pump none the less.

[newreef8584]

I can't see them working as a return pump in any conventional nature due to the nature of the design. When modded they are set up as High Pressure Low Volume and would have pretty much 0 head pressure. As soon as you added a hose they would simply cavitate.

I have not tried this, but am making a simple obsevation of the design.

[Inflames]

They wouldnt cavitate until air is introduced.

[Keelay]

I use an MJ400 for my top off pump. It sits in my RO reservoir and is connected to power through a float switch. I used 1/2" clear vinyl tubing and just pushed it on snug to the standard output. The reservoir is about 24" deep. And pushes water over to the sump without any issue.

I agree. For a small tank or a refugium feed and MJ has some potential here as is. I'm not as familiar with the mods other than the stream MOD, which would help you here.

[hllywd]

<a href=showthread.php?s=&postid=9550809#post9550809 target=_blank>Originally posted</a> by Inflames
They wouldnt cavitate until air is introduced.

Not true. Cavitation is caused by the impeller lowering pressure enough to "boil" the water on the intake side of the impeller or propeller, the bubbles collapse creating a shock wave that can damage or erode the impeller or propeller. I doubt you could cavitate any MJ, just not enough power.

I think newreef meant to say high volume, low pressure. At any rate I don't see a way a MJ mod would work as a return pump. If you weren't expecting much an unmodified one would work. I've used a 1200 with water changes and such and it worked well.

Tim

[Keelay]

<a href=showthread.php?s=&postid=9551079#post9551079 target=_blank>Originally posted</a> by Keelay
...I'm not as familiar with the mods other than the stream MOD, which would help you here.

Oops, I meant to say not help you here.

[Keelay]

Here are the listed max pumping heights listed for MJs (out of the box)
MP400 29"
MP600 53"
MP900 46"
MP1200 69"

I agree with Tim, It's very unlikely that you will ever cavitate a MJ. You're definately not going to make it cavitate by adding a hose and back pressure on the outlet.

[NanoReefWanabe]

i made my mj400 cavitate when i had a 1/2" line hooked to either side of it in a CL... :(

[DiViNeLeFT]

here you go... just about everything you ever wanted to know about maxijets as return pumps. ChemE knows his stuff.

http://reefcentral.com/forums/showthread.php?threadid=815765&perpage=25&pagenumber=1

[Keelay]

<a href=showthread.php?s=&postid=9551571#post9551571 target=_blank>Originally posted</a> by NanoReefWanabe
i made my mj400 cavitate when i had a 1/2" line hooked to either side of it in a CL... :(

Ah so someone with experience shoots us all down. Thanks NanoReefWanabe. :)

I this situation. Using it as a return pump, there shouldn't be an issue.
From what I understand... Hooking up a pipe (or some other restriction) on the inlet of a pump is what contributes to cavitation. Hooking up some pipe (or other restriction again) on the outlet alone will never cause cavitation.