A colleague used the same detergent-free products as myself using his "Mighty Fine" machine. He used de-foamer by the bucketful! I, using a more powerful Jaguar 6.6 used nil for my regular work. He couldn't understand the anomaly and neither could I.
Then he too bought a Jaguar. The de-foamer stayed on the shelf as it was no longer required.
Our conclusion was that the Jaguar had been designed to reduce the turbulence in the recovery tank leading to greater airflow/performance, a side benefit being reduced foaming.
Finally, if you market yourself on quality, command a more realistic fee for your work, cleaning fewer carpets a day but to the highest internationally recognised standards, your customers, I have found, will respect and take on board your advice about how to maintain their valuable soft furnishings between your regular visits. No foam, no abused carpet or stains and the only time de-foamer is required is to work with your chosen cleaning products. Those who work on speed and low price, rushing between new jobs/new customers wont generally have the time to talk to and educate their customers.
The JAGUAR MX-2 ETM @ cross-american.com