Various questions for central sump / grow bed / multiple display tanks setup

[Fish Tank Travis]

I'll be honest, at this point the pump discussion is getting above my level, I'm not familiar enough with that sort of stuff, so I trust your information on it.

As for the elbows, I do agree. It depends on flow levels and pipe size. So many people try to get away with using small pipes in this hobby while wanting high flow. 1" pipes just kills flow rates. I'm using 2" on all my pipes, fittings cost a bunch which sucks, but I'm getting the most flow possible out of everything.

That's the way to go about it. The bigger the better, within reason. You won't really gain anything trying to flow 1000gph through a 12" pipe as opposed to a 3" pipe. Lol. Well, maybe water volume. Haha.

Even if your end fitting that flows into your tank is only 1/2", it is still better to run 1-1.5" lines because they allow more flow with less friction. You will get more flow out of the same 1/2" return fitting if you use 1-1.5" piping up to that fitting than you would if you ran just 1/2" pipe the whole way up to it.

There are really just a ton of factors that go into how efficient flow from a pump will be. It's best to just try and oversized stuff where you can, within reason,to get the best results.