Quote Originally Posted by seadogg View Post
Thanks, that sounds reasonable. I'll probably add just one or wait and see how the new pump/filter works and then decide. Would I have better flow rate if I put a "Y" on the filter discharge and ran a seperate line to the new return instead of running one hose with two returns in series?
You'll always have lower flow at the return furthest from the pump... that's just physics... If you want to compensate, you have a couple options:

to run a Y with each line being equal length.. either by moving the pump to the middle of the two returns, or by simply wasting enough hose on the close return to even it out

or you could make the hose going to the return closest to the pump a smaller diameter (IE 1.5 inch hose going to the return on the far end of the pool and 1 inch hose for the return nearest to the pump).. changing to a smaller hose near the pump creates some back pressure on the smaller hose because it's volume is considerably lower, which allows the Y to transfer some extra pressure to the longer hose... It's a trial and error thing to figure out what sizes work best for you.

or you could add a regulator/valve on the shorter line.. by doing that, you can specifically control how much water flows through that return, effectively boosting the other returns flow.

To answer your original question about Y vs Series... I've got no idea if one will result in better pressure than the other. Ultimately, the pump will push more water through whichever path offers the least resistance, which means the shorter hose or nearest hole, unless there's something to equalize the pressure down the line. In my pool, my hoses are all 1 1/2", while the opening in my return is only about 3/4"... so there's clearly some backpressure created there.... I just don't know if it's enough to support a 2nd outlet without a significant loss in pressure.

Ultimately, I would probably not overthink it. Add a single return near your steps, and run it in series like you originally thought... If there's no pressure at it, then check the above steps for solutions... If there's plenty of pressure at both returns, you might be able to put a third return in like you originally wanted... I seriously doubt you'd get more than 3 returns and still have any sort of decent pressure coming from them.