you can use any low foam or no foam carpet cleaner....one good one is the ZEP extractor shampoo..or just the plain carpet shampoo...both cheap and they make a lot of solution with the ratio cut...
they also do a great job of cleaning...I use it in my Mytee extractor on the house rugs at times ..and does a real nice job..and they are cheap...like 8.00 a gallon and it dilutes also...
get it at Home Depot.....the ZEP citrus
APC works well also ..for some stubborn stains...
Al