need return pump size

[tropills]

hey all, I need to know what return pump size I need for a dual megaflow AGA
tank, 125 gallon, I'm thinking a mag 12 ??? it will only be returning from under the tank (in stand) thru the returns in the tank 3/4". what do any of you use ?
kinda need to know soon so I can get a pump ordered up.
Thanks.

 

[cmaxwell39]

How many overflows does the tank have. I believe the 125 has 2-- one in each back corner. If so then each one should handle 600 gph. I might go a little bigger than a mag 12 in that case. A mag 12 is rated at 1200 gph at 0 head. By the time you add head pressure due to plumbing restriction and just having to pump the water from underneath the tank to the top of the tank you will decrease the volume that it pumps from 1200 to considerbly less.

 

[tropills]

Dual overflows as I said in my first post, I know it will lose flow thru head pressure. I'm just wondering what anyone else is running,

 

[mr.m]

I use a mag 18 on my 120 with head loss i get about 1250 to 1300

 

[cmaxwell39]

Sorry I missed the dual overflow part. Read too quick. I would probably suggest going with the Mag 18. Just put a couple of ball valves in the line in order to dial back the flow if needed.

 

[natclanwy]

There is no need to overdrive a drilled tank you aren't trying to maintain a siphon like if you were running an HOB overflow box all you need is a pump to push water back up to the tank doesn't really matter what size as long as you don't go over what the overflows are rated for. A mag 18 is going to be way overkill especially since you are trying to return through .75" pipe you will lose almost half of its capacity just to the restriction in the return plumbing if you increase the size of the plumbing you will probably have to put a valve in to reduce the flow. A mag 12 will be adequate and you won't have to worry about valving back the flow and causing your pump to generate more heat because the output is so restricted.
Edit: This largly depends on your headloss also which is going to be significant unless you increase the size of your return plumbing. Using 3/4" plumbing with one 90 and 4.5 vert. ft a mag 18 will return aprx 800gph and a Mag 12 will return aprx 700gph.

 

[ameno]

So you have two 3/4" returns? what kind of flow rate are you looking for? The mag 12 recommends 1.5" for the return, so if you have two returns you can come up with 1.5" and then branch off and not lose a lot of head. So just depends on what flow you want. I'm running a mag 12 on my 125 with a 1" return and getting around 1000 gph. which works fine thru the fuge and skimmer compartment.

 

[tropills]

Originally Posted by ameno
http:///forum/post/2553965
So you have two 3/4" returns? what kind of flow rate are you looking for? The mag 12 recommends 1.5" for the return, so if you have two returns you can come up with 1.5" and then branch off and not lose a lot of head. So just depends on what flow you want. I'm running a mag 12 on my 125 with a 1" return and getting around 1000 gph. which works fine thru the fuge and skimmer compartment.
It's actually for my African cichlid tank, This is the first AGA mega-flow I've ever owned so Didn't know which pump, had a idea just wanted to be sure , so I'm going to use the mag 12, Thanks to all...