CS>PPM

[Margaret]

I see that conversation is a little slow at the moment. Then perhaps this might 
be a good time to ask a question.
When I make my CS it normally reads 12ppm (with TDS meter), but the following 
day it will drop to 5 or 6ppm.
I am aware that it is normal to drop, but by soooooooo much?
Thank you for any input,
Margaret.