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Switching from an internal pump to an external pump - heat question

r2reyzer

NJRC Member
I'm thinking about switching my Mag 12 out for an external pump (not sure which one yet). For those of you that have done that switch, did your temperature go down a couple degrees? If so, how much? I think the external pumps typically leave more heat out of your water/tank, but I wasn't sure if there was a noticable affect on the temperature. Thanks.
 
Yeah I did it on my first set up. Seemed to help with the heat. Do you have any cooling fans yet? They helped me the most I now have 3
 

r2reyzer

NJRC Member
Thanks Nick. I have a cooling fan over my main tank (125 Gallon). The fan did drop my temp. In the summer, it keeps the temp around 80 degrees. I want to switch to a larger pump, and don't want the temp to go any higher than that. In my setup, my mag 12 could easily be switched to a mag 18 since the dimensions are the same. But if there is a benefit to go external by droppng the temp down a degree or two, I'd want to go in that direction.
 

JohnS_323

Officer Emeritus
Officer Emeritus
A relatively inexpensive way to get more flow out of that pump is to switch the impeller with one for a Mag18. It gives you something like a "Mag15". We did that with our Mag12 and it definitely increased the flow. It doesn't help your heat issue though.
 

r2reyzer

NJRC Member
JohnS_323 said:
A relatively inexpensive way to get more flow out of that pump is to switch the impeller with one for a Mag18. It gives you something like a "Mag15". We did that with our Mag12 and it definitely increased the flow. It doesn't help your heat issue though.

I like that suggestion John. I'll keep that in mind. However, chances are that I'll go with an external pump. I'll probably put the Mag 12 up for sale...maybe someone else could use that idea? :D
 
I mounted a mag pump externally. I really can't say if it reduced heat because it was never run with the mag in the sump. But the pump does work mounted externally. They say you can use them either way.
 

r2reyzer

NJRC Member
Thanks Steamman. Yea, I was thinking about doing that. But I do need to upgrade my flow so I would need to go to either a Mag 18 or a more powerful external pump. If I'm going to make the switch, I think I'm going external. Thanks for the input.
 
Ray - having used smaller mags before on my old 55 - i can definitely say they added a degree or two to the overall temp. One for the skimmer, one for the return (back then i probably should have just gotten a single one and plumbed it). Anyways if you have the room to go external - I definitely think that will help. Just make sure you add an appropriate union valve so that if the pump needs cleaning or goes out - you can just turn a knob and take the pump out for servicing.

One thing I noticed on my old mags was the screws rusting. Also sponges, vermitid snails and other critters woudl colonize the pump. Going external you avoid all that on the pump itself.
 

r2reyzer

NJRC Member
Thanks Hawk. The screws are rusting on my current Mag 12 and it's only about 7 months old. With all the feedback, I'm def going external. My tank is in my basement built into a wall. The room behind the tank is a storage closet, but my wife now calls it the fish room becasue there's more "fish stuff" than closet stuff. So I definitely have enough space. Thanks for the feedback.
 
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