Newbie manifold questions

[archangel91]

I'm in the planning stage of setting up a 120gal display with a 40b sump and have a couple of questions I was hoping someone could help me out with.

The tank is pre-drilled with 2 overflows (offset center), each having a 1" drain and 3/4" return.

Looking through the pristine plumbing thread and a bunch of build threads, I'm planning on using a manifold to keep everything clean, but I'm a little confused on the size plumbing I should be using and if I can plumb it off of my return pump or if I should use a second pump. In total I'm planning on having 7 outputs with each having its own gate valve to control flow - 2 returns, 2 reactors, ATS, chiller, and 1 spare in case I need to add something later.

With my return's already set up for 3/4", should the entire system be plumbed in 3/4" and then just reduce the other lines after their respective gate valve, or is there a benefit to oversizing the manifold and then reducing the return lines coming off of it?

For the pump I was originally thinking about one of the new Ecotech Vectra pumps, but since those are not Apex compatible I'm now leaning more toward the Waveline DC10000II.

any advice would be greatly appreciated

 

[username in use]

IF you are using a single pump, the output of that pump is going to be more than that of the 3/4" return line. So I would oversize for the manifold. Do a full 1.5" manifold section that reduces to the 3/4" return line at the end.