The 1⁄2” copper pipe end of my counterflow chiller returns to the sink to fill either a bucket for Powdered Brewery Wash or sanitizer. Water boiled in PBW is gravity-fed from the brew kettle through the chiller, followed by Iodophor or Star San sanitizer. To sanitize before use, I made what looks like a new car fuel pump cartridge. I drop an aquarium pump in a tall tubular container (I think it had Cheerios in it) with precut clear tubing. It slips into the center of the chiller perfectly, holding it securely. I circulate for 30 minutes before hooking my beer lines to it. I can submerge the entire container in my sink of sanitizer to get the right proportions.