Return jet fittings.....does size matter?


Well-known member
Feb 8, 2008
Milford, CT
Ive been looks like my pool has 2 different size return jets. The thread sizes are the same, but the opening for the return water seems smaller on one than the other.

My question is if this makes a difference? I would think it does, smaller opening = higher pressure (and more backpressure against the filter/pump).

If this is the case, is there a "rhyme to the reason" of what size goes where? Right now I have the smaller diameter opening in the shallow end, the larger is in the deep end. Im wondering if they should be swapped (I inherited this pool, so I have no idea why there are two different sizes).

Has anyone seen the Pentair eyeball fitting that comes with different size discs to adjust the water opening? Im thinking about trying those, to see if I can improve/pinpoint circulation better than the standard eyeballs.




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Platinum Supporter
TFP Expert
May 7, 2007
Silver Spring, MD
Typically smaller eyeballs are put on returns that are closer to the pump and larger eyeballs on returns that are further from the pump, when the returns are all plumbed on a single pipe run, so that the flow is about the same from all of them.