Plumbing sizes

Reef Central's Head Loss Calculator

Allows you to insert variables to calculate head loss, but I'm sure you've seen this.
The only thing that I've ever read/found is that you reach a point that additional diameter doesn't create any additional gains.  It looks somewhat odd, but I'm running 1.25" PVC for my return using an Eheim 1060 rated @ 607 gph for an estimated volume of +/- 420 gph into the tank. 
-Eric

 

Yes you would!

For instance, think of it in reverse:

My Eheim has a 1/2" outlet from the pump.

Using this calculator, and running 3/4" PVC for my return (calculator stops @ 3/4"), my volume would be approx. 340 gph whereas with the 1.25" it is approx. 420 gph.
I don't know how linear the calculation is, i.e. so I can figure the 1/2" volume, but in looking @ the numbers versus the return size it would certainly be below 300 gph (guessing 270) if I would limit the return to the 1/2" output size.
So to tie up my early morning ramblings, a larger diamter is needed to carry the volume for the distance, and although your bulk head is a deciding factor, it isn't the only one.
With your setup, I would assume the manufacturer has designed the overflow to handle between 600-800 gph, which if using as equipped would be the number to shoot for. 
However, if you're looking for more flow, you could use both the bulkheads and combine them as an overflow.  Or you could use them to create a silent overflow, in both instances using an over the tank return.
Strange on the bulkheads - I thought one would be 3/4" and one would be 1".
-Eric

 

Not to step on any toes but really there is no reason to use any bigger pvc then your bulkheads. I learned quite a bit about pvc and pressure loss and all those various things in my irrigation classes. To put it simply though just use the largest size of your bulkheads or pump allows.

 

I would use 1/2 because you wont gain anything with the 1". There is a reason these pumps are designed the way they are.

 

AJ-

Unless you are plumbing +/- 1' or so, I would do some more research before you use 1/2" PVC.

What are you running...12' up and how many feet over?

Let's say you had a Little Giant 4-MDQX-SC, just for argument's sake.  And let's say you wanted to pump 12' up and 5' over (horizontal doesn't make a huge difference), with 6 - 90 deg elbows.
Now, with 3/4" PVC, your gph would be approx 360 gph and with 2" PVC you'd be at 612 gph.
So...while a 1" bulkhead can handle 600 gph - if you plumb with 3/4" you'll only be getting 360 gph to that bulkead, right?  Versus 2" where you'd be delivering 612 gph to that same bulkhead.
This calculator won't even figure 1/2" so I can't imagine how low it would be.
-Eric

 

thats what i plan on doing cept i'm going to T mine off at the tank since i dont have any bulkheads. maybe use a SCWD

 

That calculater is pretty damn cool. It made me lean over the fence a little more towards moderate pipe size.

 

some people call them squids, its a non powered flow alternater, it alternates flow from one output to another. you lose about 20% of your pumps power by doing it though. the pictures of it look like a black human heart haha. but have heard of them sticking and stuff too. but if you use filter floss or something i dont see why anything should get in there. and they are fairly reasonable priced

 

Posted By apjohnson on 05/29/2009 10:19 PM
SCWD?

Switching Current Water Director (SCWD)







*
Produces waves with your existing aquarium pump

*
The most energy-efficient aquarium wavemaker available

*
Creates bidirectional water movement for your reef aquarium



The most energy efficient wave maker available! SCWD uses your existing pump to create bidirectional water movement in your reef aquarium. Plumbed inline, SCWD directs incoming water to two alternating outputs, switching automatically at a rate depending on incoming pressure. Install the 3/4" SCWD with 3/4" tubing and system pumps with flow rates from 50 to 1,400 gph. Install the NEW 1" SCWD with 1" tubing and pumps with flow rates from 500 to 3,500 gph. Use clamps to keep tubing in place (use stainless steel for external locations; plastic for internal).
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=10668

-Eric