Good morning SK,
Do you have ILEO or colo? I forgot, however, know that I get 5-7 days/wafer and then I use one pouch that lasts 4-5 days/week. After emptying, I backflush with a glass of warm (not hot) water, and that keeps me feeling extra clean. Just so you know, those pouches range in price from 5-10 dollars a piece. If you use a drainable, the backflushing works great, and if you use the closed end (I don't know what to say), I don't like or use the closed end. As far as swimming goes, as long as you have a good seal on the wafer and depending on whether you swim in the ocean, salt or fresh water will determine how long after swimming you might have to change. If it's just a pool, there should be no difference in wear time. Michael :)
As far as what to do with the pouch, just empty before swimming, and depending on output or how soon after you eat, it will determine how long it will be before it fills up and you might want to get out of the water. This past summer, I swam in the Gulf of Mexico for 4 straight hours without getting out and not even knowing I had a pouch. Know that because the salt level is so high, after each swim that night, I would change the wafer. That's all. Hope some of this helps.
PS. There is nothing special that I do other than making sure it's empty upon entering the water. That's it because my seal on the wafer is always good. I too am a swimmer and a diver. And I have no problems. Michael