Return pump/plumbing experts needed!

[Rhinecanthus]

I would like some feedback on the following pump issue:

First of all, here are the specs from the pump to the return:

52" vertical (1" Flex PVC to 1" Rigid PVC)
6" linear
1 ball valve
2 unions
1 45 elbow
2 90 elbows
3/4" locline outlet (2 nozzles)

Overflow: I calculate/estimate around 400-450gph

So right now I have a Mag 9.5 on there dialed back to about 60% of max.

When I plug in the numbers to the ReefCentral calculator for a Mag 9, here is what I get:

Mag 9.5: 630 gph, 7.24ft head pressure @ 3.13 PSI

Mag 7: 401 gph, 5.5ft head pressure @ 2.30 PSI

Now, I like the lower numbers of the Mag 7 compared to the Mag 9.5 which means I can probably run the Mag 7 close to wide open.

My question is this...would swapping out the Mag 9.5 for the Mag 7 be a good idea or should I just leave the Mag 9.5?

I assume that the added pressure can shorten the life of the pump, not to mention add more pressure to my plumbing.

Problem is, the Mag 9.5 is already on there...so I guess I am looking for an excuse NOT to have to buy a new pump and do the switch.

Can anyone see any logic either way based on what I posted above?

Thanks!

[shawnz28]

What is the reasoning for needing to switch the pump out in the first place? Are you having heat problems or anything?

[Rhinecanthus]

<a href=showthread.php?s=&postid=7234407#post7234407 target=_blank>Originally posted</a> by shawnz28
What is the reasoning for needing to switch the pump out in the first place? Are you having heat problems or anything?

Not particularly...although the hot summer hasnt hit yet.

Cost difference would be about $15.00/YEAR.

I guess just because I have always gone with the logic that its better to let a pump run wide open than restrict a more powerful pump and put more stress on the motor.

[poppin_fresh]

What I dont understand is why is the head pressure different for the two pumps? Your plumbing is the same, so how can one pump be over 7' of head but the other 5.5'?

I'm not totally familiar with the Mags, but are the outlet sizes different?

What size tank is this for? You could probably scale back the pump, but are you going to gain anything? Is the power savings of a 9.5 versus a 7 going to save $.50 a month? If so how long will it take to recoup the money spent on the 7? My guess is a long time, but at least you have something to think about.

[Rhinecanthus]

<a href=showthread.php?s=&postid=7234446#post7234446 target=_blank>Originally posted</a> by poppin_fresh
What I dont understand is why is the head pressure different for the two pumps? Your plumbing is the same, so how can one pump be over 7' of head but the other 5.5'?

I'm not totally familiar with the Mags, but are the outlet sizes different?

What size tank is this for? You could probably scale back the pump, but are you going to gain anything? Is the power savings of a 9.5 versus a 7 going to save $.50 a month? If so how long will it take to recoup the money spent on the 7? My guess is a long time, but at least you have something to think about.

Outlet size on the Mag 7 is 1/2" and Mag 9.5 is 3/4"

Savings would be about $1.00/month...negligible.

Again, thinking more of saving the pump motor...I know Mags are reliable but dont want to push the pump too much.

[poppin_fresh]

If you are worried about the head pressure, just "T" off and return some of the output to the sump. It will reduce head pressure and allow you to controll flow to the display.

[Rhinecanthus]

<a href=showthread.php?s=&postid=7234500#post7234500 target=_blank>Originally posted</a> by poppin_fresh
If you are worried about the head pressure, just "T" off and return some of the output to the sump. It will reduce head pressure and allow you to controll flow to the display.

Thats not a bad idea...I could split into a "Y" and have another ball-valve and let the return back into the sump...I could even use THAT split to give more flow to the carbon/phosphate remover media that is in the sump.

Also, when I go to do a water change I could simply use that end to pump water from the sump rather than siphoning from the main tank.

[Rhinecanthus]

poppin_fresh

Want to know the sad part? Thats how my LAST tank was set up and I didnt even THINK of doing that!!

Loooong weekend!