Had a call today from carpet cleaner who is using eco-spotter on a regular basis and has had several call backs because it has been leaving a dark circle around the spotted area.
Couldn't understand what he meant until I met with him today a job he did on Monday with the same problem.There were 10 areas that stood out clearly on the carpet and the lady was not very amused

It was quickly resolved when I got the CFR off and extracted with just water the spots where he had applied the eco-spotter and the mark dissapeared.Took 10 minutes at most.
He has been using it for spotting but not extracting afterwards and this has been the problem especially on wool carpets which these were today.
He says he has done loads of jobs like this as he thought it would just evaporate away,clearly it hadn't. Are others doing the same? Have you experienced a similar problem?
I am posting this info with his consent as he does read these boards
