I've just cleaned mine on day six of a brew; it had quite a lot of 'crud' on top. The SG jumped from 1.006 to 1.012 but seems to be settling down now, after three hours!!! I did rinse it in hottish water, but only for ten seconds. Look at my chart.
https://docs.google.com/spreadsheets/d/1zJ4lFaQWrNnSW4ZZGk17kNl6CMaB4J9cg2Obw-_nerU/edit?usp=sharing
https://docs.google.com/spreadsheets/d/1zJ4lFaQWrNnSW4ZZGk17kNl6CMaB4J9cg2Obw-_nerU/edit?usp=sharing
