Plumbing Diameters

[kaOzGrUnT]

So I am doing the plumbing on my new 90 Gal set up, I will use an external pump as the return (little giant 4 MDQX SC) and a Mag Drive 9.5 as a close loop.
The 4-MDQX-SC has 1" FPT and 1"MPT, BUT I measured the actual inner circumference and its 3/4", should I be Using 3/4" PVC pipe or 1" PVC pipe?

The Mag Drive 9.5 has 3/4" FPT and MPT, I haven't had the chance to measure the inner part because is currently running on my old tank.

Thanks again for all your help.

Overflow is from glass-holes.com 1500 gph
little giant rated at 1350gph at 1' head
mag drive 9.5 rated at 950gph at 1' head (used for closed loop)

 

[VJ&POOPS]

Why are you using two pumps? Use a bulkhead that fits the hole, regardless of the size of your plumbing. The size of your plumbing is usually based on the head (length of pump flow to destination) and the gph for return and overflow.

 

[albano]

I think you should use the 1"...more flow, less restriction...if you upgrade pump, you are already set!

 

[motortrendz]

go with the 1in.. and if u put a ball valve on the return size u can adjust the flow to whatever u want.. if you output is 3/4 u can go to home depot ad get a 3/4 to 1" adapter and your set

 

[kaOzGrUnT]

Head pressure

just throwing a thought out there, if the intake and output are 3/4" and you put a 1" piping, wouldn't you be adding head pressure to it? hear me out.....
the pump is kicking out water at a 3/4" port and the moment you let it loose on a bigger diameter you create turbulence thus creating head pressure in a vertical pipe. (the picture works a lot better in my mind)
BUT if you keep it the same size the whole way it runs smooth.:smash:
like I said the theory works in my mind but I am no scientist.

Opinions?

 

[motortrendz]

actually if you read the box on the magdrives.. it does say if you wan max output of the units it recomends stepping the output up... i forget what the % of increase is.. when i get home tomorow ill look, unless you have the box.. or i could be loosing my mind and mkaing it up..lol its been a long weekend, but im pretty sure!

 

[Imbarrie]

If you increase the output diameter you increase the volume of water which adds weight. That will reduce the efficiency because the pump works harder to overcome that.


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[motortrendz]

i understand the theory, but your not going from a 3/4 to a 4in tube.. its only going up a 1/4 of an inch..

 

[kaOzGrUnT]

If you increase the output diameter you increase the volume of water which adds weight. That will reduce the efficiency because the pump works harder to overcome that.


Sent from my iPhone using Reefs

that's what i'm talking about... lol my brain still thinks outside the box.
so what do u think about my plumbing question?

 

[Imbarrie]

Going up 1/4 means an increase of 33%. That also increases exponentially as distance increases.

There has to be a chart of this online.


Sent from my iPhone using Reefs

 

[motortrendz]

im pretty sure it says something abt it on the box.. anyone have one handy? lol only reason i think i saw it was bc i had the same question.. and i was reading the outputs and flow rates and it said something abt it.. im not home tonight so i cant go look for ya...

 

[kaOzGrUnT]

I came across this in the internet, I hope it helps the discussion.
http://www.flexpvc.com/WaterFlowBasedOnPipeSize.shtml
It kind of answers the question I had, If your pump is rated at 1300gph you want to use 3/4", if you use a 1" pipe you will have "cavitation" due to "not ideal pressure" and this damages the pump.
Interesting

 

[motortrendz]

interesting...

 

[cali_reef]

just throwing a thought out there, if the intake and output are 3/4" and you put a 1" piping, wouldn't you be adding head pressure to it? hear me out.....
the pump is kicking out water at a 3/4" port and the moment you let it loose on a bigger diameter you create turbulence thus creating head pressure in a vertical pipe. (the picture works a lot better in my mind)
BUT if you keep it the same size the whole way it runs smooth.:smash:
like I said the theory works in my mind but I am no scientist.

Opinions?

You are correct about the additional head pressure placed on the pump when oversize on VERTICAL runs. You should always use the right size piping on the pressure side of the pump, as any good pump's specs is rated based on this optimum size, go bigger or smaller will alter it's performance.

When the pipes are lay horizontally, there is little or no head pressure, bigger pipe will help by reducing friction and provide better flow path.

 

[kaOzGrUnT]

So I'm not alone on this one, I will keep inside diameter of exit port BUT I will go to next diameter on the IN port.:tub: