Mag 12 internal or external?

[Jeremy Blaze]

I am going to use a Mag 12 as the retunr pump on a tank I am setting up.

I am trying to decide if I should run it externally or submersed in the sump.

If it is in the sump, I am thinking it may add more heat to the tank, but it may be a bit quiter.

[whiteshark]

I think dealing with the noise (if there is any) is better than having to get a chiller (which would probably make the same amount of noise).

[Alaskan Reefer]

Agree with whiteshark. That's why I prefer Eheims -- no noise, no heat loss.

[jent46bow]

I run a mag 12 and mag 9.5 extenaly to run my CL. no major noise issues. In this case I would rather lessen the temp of the tank though if possible.

[Craig Lambert]

Aren't mags suppose to run internal? I think that's the recommendation on the box.

[pledosophy]

Mags used externally can overheat and cause so major problems. They are meant to be used internally.

[bureau13]

I'm pretty sure the box on my Mag18 said internal or external, but Marine Depot recommends specifically that they not be run externally, so who knows. Someone mentioned that, run externally, they sometimes leak, but I have no idea...I've always run mine internally.

jds

[mfinn]

I have a mag 12 that is on a closed loop that is external.
It does say right on the top of the box,"Use in or out of the water".

[asfullax]

My mag 9.5 is running external and has been for abour 5 years. No problems and all I have done is replace the impeller once. :D

I vote for external due to the heat and at least with mine, the pump produced significantly less noise externally then internal in the sump.

[asfullax]

oh yeah,

My mag 9.5 box also says use in or out of water. They even included a few adapters to go from fittings to hose.

[Kaiser Tang]

How big is your tank/sump? Most likely a mag 12 won't add any noticiable heat. It won't add heat like lighting does.

[Jamesurq]

If you have the option to run an external pump - go with something better than a mag.