Difference between 1.5" and 2" drain in overflow

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I'm running 2-2" Dursos and drilled one vent hole in each cap matched for when first running ~2000gph. Strangely they are different sizes (5/32 and 7/32 just checked with an index) but generally overall they are small. Only about 1000gph now but holes still working, not Herbie silent but the Dursos are really really quiet.

Do remember would get the up/down and sucking in the overflow with cap and no hole, small hole would get the variation in the overflow level but no sucking and still a little noisy but once hit the right hole size, the sound just dropped off level stabilized.

Now if I see the level in the overflow moving a bit, know I have a little salt creep to clear.