Have a look at the build project as it may give you some ideas.
Stealth Cooling Project
It's not finished yet but I got down to one fan in the entire system, (PSU), and the hdd'S were then the noisiest items, although with a little cheating I had total silence briefly. I split to all blocks via the manifolds you can see at the bottom, which is better than going through all the blocks with one pipe run. I'm also using an Eheim 1250 which can be used submerged or inline, you can see a pic of it submerged in the project link and a earlier pic of it inline
HERE, (with my pet slug "Boris" in the background
)