Mag 7 downgrade to Mag5

[DMBillies]

I have a Mag7 that's pushing a little bit too much water for my purposes. I think I heard somewhere that you can just replace the Mag7 impeller with a mag5 impeller and get a reduced flow rate. Is this right? If so, is there anywhere local that they carry Mag5 impellers?

[rcmike]

I think you can. You could also just put a ball valve on it as well. I think aquatic critter has the impellers, or at least they used to.

[crumbletop]

Yes, I'm pretty sure you can make a 7 a 5 by just changing the impeller. I don't know where to get one locally, though.

[rsteagall]

<a href=showthread.php?s=&postid=9391834#post9391834 target=_blank>Originally posted</a> by crumbletop
Yes, I'm pretty sure you can make a 7 a 5 by just changing the impeller. I don't know where to get one locally, though.

can you make a mag 5 into a mag 7 by replacing impeller?

[crumbletop]

I'm pretty sure the pump for the mag5 and mag7 is the same, and the only diff is the impeller. This is what I was able to find via a search:

Mag3 = 12575 impeller + 12535 pump cover
Mag5 = 12575 impeller + 12545 pump cover
Mag7 = 12585 impeller + 12545 pump cover

[DMBillies]

Thanks guys for the input. I tried calling every store in the area and no one has one. So, I'll just have to order one.

I don't like throttling pumps back very much because of the stress it puts on them. If I can do something as easy as changing an impeller, it's a simple (and pretty cheap) fix. Also, I already tried throttling it back and it makes a lot of extra noise :) ...which may mean it needs a new impeller anyway.

[rcmike]

Actually the pump draws less current if it is throttled back some. It shouldn't stress it to close it off some. Of course if it makes it noisy I wouldn't do it that way either. I have a quiet one pump that is the opposite. It is very noisy wide open but is quiet when restricted.

[Angela Short]

I have a Mag 5 you can swap the impeller out and see if that does the trick for ya :) Its just used as a water change pump/ spare pump so it isn't important what it pushes. I also have read you can interchange the 5 and 7's.

[Siffy]

I was going to make the same offer as Angela. I have a Mag 5 I was thinking about replacing with a Mag 7 for my next setup's return.

[waynesworld]

Me too I was thinking the same thing but two in front of me.

[Kalied20]

Well dang...I was thinking that too....lol

I want to move my sump return from a 5 to a 7.

[pitbullpooch]

double post

[pitbullpooch]

<a href=showthread.php?s=&postid=9392230#post9392230 target=_blank>Originally posted</a> by DMBillies
I don't like throttling pumps back very much because of the stress it puts on them. I actually read somewhere that its better for a pump to be throttled down. I read it when i was looking into buying a pump a while back. I believe it was the mag 7 that i was looking at when i read this. after reading this i planned to go to a larger pump and then throtleing it down to save some stress on the pump but ill have to read some more to see if this is true.

[DMBillies]

Ok, so perhaps I'm wrong about the throttling it back causing stress. I've read that in places before, whether it's right or wrong. In any case, the pump gets louder when I throttle it back any more, which is a no-go for an office tank.

Angela... PMing you.

[pitbullpooch]

<a href=showthread.php?s=&postid=9395869#post9395869 target=_blank>Originally posted</a> by DMBillies
Ok, so perhaps I'm wrong about the throttling it back causing stress. I've read that in places before, whether it's right or wrong. In any case, the pump gets louder when I throttle it back any more, which is a no-go for an office tank.

gotcha. just thought id let you know.

[c_stowers]

Throttling pumps back to increase the efficiency/longevity of the pump depends on the pump curve for the specific pump. Unfortunately, most data for aquarium pumps don't include motor efficiencies and NPSHR (Net positive suction pressure required) and many other useful parameters for choosing the correct pump for your application. If you don't want the noise, but want to reduce the flow, you can always put a "T" then a ball valve and divert some flow back to the suction side. This does not put additional head pressure on the pump, but can sometimes be difficult to plumb (depending on your system).

[pitbullpooch]

<a href=showthread.php?s=&postid=9404709#post9404709 target=_blank>Originally posted</a> by c_stowers
Throttling pumps back to increase the efficiency/longevity of the pump depends on the pump curve for the specific pump. Unfortunately, most data for aquarium pumps don't include motor efficiencies and NPSHR (Net positive suction pressure required) and many other useful parameters for choosing the correct pump for your application. If you don't want the noise, but want to reduce the flow, you can always put a "T" then a ball valve and divert some flow back to the suction side. This does not put additional head pressure on the pump, but can sometimes be difficult to plumb (depending on your system). thanks for that info c__stowers. That makes alot of sense. It took me a little thinking to figure out where exactly the T goes but i figured it out. Its to early to use my head lol.