Starsan isn't a cleaner... I don't worry too much about my chiller being clean other than not having any crud collected on it like hops or other mess from the previous boil. When I use my chiller, I take an empty bucket and fill it with the 'first runnings' from my chiller as I use it. When I'm finished chilling, I move the chiller into that bucket of warm water and let it sit for a while to dissolve and remove any sticky crud from the boil. It probably wouldn't hurt to put some oxiclean in that bucket also. As I'm cleaning up, I pull the chiller out and remove any crud that might still be on it with the garden hose and put it away...