How much solution should be used?

[Bernd]

Some carpets are extra dirty and seem to inhibit the foam.  
I would run the mix a little bit heavy when that happens.  
You may need to padcap or HWE if necessary certain areas.

Thanks for your reply. The carpet was just light to medium soiled.

The result was ok...but i was wondering cause there was no foam.

What is the average solution you have to use on for example 300 square feet ?