These people are very nice and very knowledgable. As a previous reviewer stated they've been in business for years and years.
Unlike some of their competitors they're very knowlegable and always seem to have the hard to find part no one else stocks. I never get the feeling they're trying to sell me something I don't need.
I'm a do it yourselfer and I'm always trying to save a buck and figure out how to bandaid my aging pool equipment. Swim-In is always helpful and their pricing is reasonable. Typically I'm there during the week on my lunch hour and it's not crowded but I'm not sure if they get busy on the weekends.