Fletch
Something is very wrong, with what you're doing.
A ltr of chemical per job is just plain crazy, unless these are very big jobs, but are they, or are you just dumping chemical into your machine.
Get yourself onto a course and you will find out about the realities of cleaning and the basics of diluting, prespraying and rinsing / flushing.
You can purchase powders for as little as £18 per 10 Kilo tub and 5 litres of presprays or carpet cleaner for around £5, which will give pretty amazing results.
So, you could do 15 jobs per week for around £5.
robbie