hmm... i just realized that i should definitely route the return back to the tanks.
The problem (i think) with returning to the feed line is: if a vapor/air bubble enters the return then it is stuck in a loop with nowhere to escape.
By returning back to the tanks, I hope that bubbles would naturally escape the return line and I won't have to worry about them entering the feed line.
I'll probably bite the bullet and add another crossover so the return can tee into both tanks.
