Go with polyester or PBT for pool swimwear.

Polyester or PBT (a polyester variant) is your answer. Nylon and spandex break down fast in chlorine—you’ll be holding up faded, saggy fabric after a few weeks. Polyester holds color and shape two to three times longer.

Spandex is stretchy, sure, but it’s the enemy of chlorine resistance. Most “blends” you see (nylon/spandex) are built for surf and sun, not daily laps. Look for a fabric labeled “chlorine-resistant” and check the tag—if it’s mostly polyester or PBT, you’re set.

Lycra Xtra Life (a branded spandex) lasts longer than standard spandex but still loses the battle to polyester over a season. For a suit you use a few times a week, polyester wins. You won’t get quite the same soft hand feel, but you’ll get a season or two more out of it.

Skip the spandex unless you like shopping for swimwear every spring.