What size return pump

[galaxy14]

I'm looking for input for my return pump. My tank is a 48 inch long by 30 wide by 30 tall set up peninsula style. It has one return with 2 nozzles out of return. I'm thinking a mag 12 ? Please give me your recommendations

 

[Eckolancer]

I have 2-1" drains and 2-3/4" returns. Im using a mag 12 and think I should have gone with a mag 18.

 

[Mike M]

Part of the decision will revolve around the size of your return plumbing, length of run, and whether you will feed other things off the return like a chiller. A chiller, for example, will cut down on your return flow by a lot once you add in the extra plumbing to go to and from the chiller along with the pressure loss from feeding a chiller. Based on what I've researched, the Mag 12 and Mag 18 are the same pump with the exception of the impeller assembly. Hence, if you have a Mag 12, you can drop a Mag 18 impeller in there later and basically upgrade it. Or you can go from an 18 to a 12 by switching out the 18 impeller for a 12 impeller. I've done these swaps and changes myself to go back and forth from a 12 to 18 and vice versa. If you are buying used, the "B" models are the newer ones and easier to find parts for.

Other Mag Drive swaps and upgrades you can do: Mag 3, 5, and 7 also share the same motor block. Mag 3 and 5 use the same impeller and just have a different cover. The Mag 5 cover has a larger inner diameter outlet and you can actually drill a Mag 3 cover outlet larger to turn a Mag 3 into a Mag 5 if you don't want to buy another cover. The Mag 7 uses a different impeller from the 3 and 5 and uses, I believe, the Mag 3 cover. The Mag 9.5 uses a different motor block and impeller from the others.

 

[Eckolancer]

@MBSL55 wrote:

This is very good news for me So you are saying if I have a mag 12B just buy the Mag 18B impeller and I will now have a mag 18? also, I have an older Mag 3 that has a broken cover. So, if I buy a mag 5/7 cover and impeller I will now have a mag 5/7. That is great news since I could use the extra presser for return and wanted to replace my salt water mixing pump with a bigger one.

 

[Mike M]

@Burbarry wrote:

This is very good news for me So you are saying if I have a mag 12B just buy the Mag 18B impeller and I will now have a mag 18? also, I have an older Mag 3 that has a broken cover. So, if I buy a mag 5/7 cover and impeller I will now have a mag 5/7. That is great news since I could use the extra presser for return and wanted to replace my salt water mixing pump with a bigger one."]

Yes indeed, just get the Mag 18B impeller and you are good to go. Plus you can just hold on to your 12B impeller as a spare just in case or just sell it.

On the Mag 3 you can just get a Mag 5 cover and you'll get the flow rate of Mag 5 as they use the same parts other than the cover. Mag 5 and 7 share the same cover but you would need a new impeller to go to a Mag 7.