I have read several posts regarding converting from Baquacil to chlorine. In the fall when winterizing I empty my sand filter prior to bringing the pump assembly indoors for winter. I want to convert this spring. I read about changing the sand after the conversion, but do I need to fiil my filter with sand, then convert, then change sand or can I convert, then add new sand? Also I plan on buying the TF-100 test kit, but does it measure the bacquacill content? If not, how do I measure? Just need a little help. Thanks.