I finally broke down today and turned on my baseboard heaters (blech). Before now, I've been keeping a crockpot full of water going. I started using filtered water after I noticed I ended up with precipitate without filtered water. Even with filtered water, there are white deposits all over the crock and lid (calcium? lime?). I could use CLR to clean it, but I don't have any around and prefer not to use heavy chemicals on my cooking surfaces. I tried boiling vinegar water with no joy. I may try baking soda water, but that's a lot of baking soda and it may still not work. Scrubbing is ineffective enough that I need something else to give me an edge. Cleanser may help, but may also wear away the finish on the crock.