What return plumbing should I use

[JCSReefing]

I have one set of plumbing that comes up from the return bulkhead, hits a T and reduces down to 1/2 loc line. The other is from my old tank that comes straight up from the bulkhead return into a 3/4 reducer, a loc line Y into two loc line. Which one would work best? See pics

 

[JCSReefing]

I have one set of plumbing that comes up from the return bulkhead, hits a T and reduces down to 1/2 loc line. The other is from my old tank that comes straight up from the bulkhead return into a 3/4 reducer, a loc line Y into two loc line. Which one would work best? See pics

 

[Sacohen]

Either one does the same thing except the T will get the returns further apart.
So it depends on where you want the water to exit the return.

 

[mfinn]

For myself, I would use the return with the least amount of pvc pipe. ( first picture)