In custy's house I asked her had she had her carpets cleaned before. She replied that her husband cleaned them every 6 weeks or so. So why was I cleaning them? Well becasue he had got fed up with doing this so often.
"How", said I, "did he clean them?"
She replied," Well, he sprays vanish all over the carpet and then steams it off!"
This explained why my waste tank was filling with foam to the top about every 2 minutes, even with a de-foamer in.
Eight months on and two further cleans from me (and none by the husband) I have got the residual foam down to just about an acceptable level which will improve again on the next clean.
Mustn't grumble too much, I charged extra for the time taken for the multiple clean-outs of foam, and she was so pleased with the results I am now cleaning the other 13 properties she owns (and which thankfully her husband has never been near with the Vanish.)