So, you recommend against the overflow box? like in the ghost or shadow? I havent heard any bad things about them so i am curious. I am trying to keep things as simple as possible. and i just figured i would gain surface skimming and it would allow for easier set up as well?
What purpose does the multiple unions serve?
I will probably be using a dart/snapper reeflo pump (not too bugged by the noise).
Absolutely use an overflow box. I would never recommend anyone not use a box. I tried it and am not a fan of how risky it would be set up wrong, hence my comment not do it. You want the flexibility overflows bring.
I have never used the shadow but considered ordering the one from Synergy. I may still do that when I get around to that tank.
Unions thread together easily but keep things water tight. It makes plumbing in manageable chunks much easier and final assembly a couple minute job. It also allows you to take it apart after everything is solvent welded to repair, replace or upgrade plumbing, pumps etc... Great choice on the Reeflo. From a value perspective, unions are to plumbing, what a sump is to filtration, if that makes sense.
Edit w/Example: the union is attached to the bulkhead under the stand. It’s the top piece. I plumbed everything to that location then simply thread it together. This system has a few certain angles I had to hit to max out flow (flex PVC is a great option to elbows but requires some skill) due to sump location.