You would usually just put it in a sock or stocking and hang it over a return flow. Or you can put it into a T-shirt in the skimmer if your skimmer has a bypass pipe so that clogging it doesn't cause any problems. Most people do the former sock method; I've done the T-shirt in skimmer method and it all dissolves within 24 hours, often within 12 (with the pump running the entire time). The Instant Pool Water Conditioner you are talking about does dissolve faster, but it's about twice as expensive per CYA ppm.