The comb drags in a way one rinse and one shampoo never quite fix. You've blamed the chlorine, picked up a swim shampoo from the pool-supply aisle, and the strand still feels like dry rope by week's end. The biggest fix happens before you get in the water.

Dry hair drinks pool water. Already-wet hair drinks much less. Stand under the regular shower with clean water until the strand feels heavy and uniformly wet root to tip. There's simply less room left for the pool water to take in. Most people walk past the rinse shower because they think it's for feet; this is the move that costs nothing and makes every other step work harder.

A thin film of leave-in through the lengths, about two pumps for shoulder-length hair, or a few drops of oil if your hair runs coarser, gives the water something to fight through before it reaches the strand. Silicone-based leave-ins hang on the longest; pool water doesn't rinse them off as fast as lighter creams. The barrier slows the water without sealing it out.

The slow problem after a month of swimming is mineral buildup. Calcium and copper layer onto the strand week after week, which makes the hair feel coarse and look dull no matter how much conditioner you pour on. The faint green tint that sometimes shows up on lighter hair is copper from old pool plumbing, turning green where it meets the water. People assume the pool turned their hair green from chlorine. Copper is the actual culprit.

The shampoo that strips mineral and salt buildup is what solves this. About once a week if you're in the pool several times a week, every two to four weeks if your hair is fragile or you only swim now and then. Daily clarifying does too much. It takes the scalp oil with the minerals and leaves the hair clean and brittle at once.

A clean-water rinse within minutes of climbing out, before the locker-room sit, gets most of the pool off before it settles in. A cap helps but doesn't seal; the pre-rinse and the leave-in matter more. If your hair is fine, your swims are short, and the comb glides through that evening with no complaint, you can skip most of this and reach for the mineral-stripping shampoo now and then.

For everyone else, your everyday shampoo doesn't have to do anything heroic. The comb tells you when you've got it right.