Crystal green is great, used it today..
Sprayed some down on some trashed carpets after using Powerburst pre spray, ( had it in tank and just sprayed using the wand),
extracted and came up really clean.
I'll sometimes rinse with water, i'll sometimes add some in tank to give it a kick..
I use either crystal green or premium clean, the engineer that fixes my machines advices these as double clean gunks up the pump head.