What i do is buy 2 gallons, one gallon is the first pass, the second gallon is the second pass. I use a paint strainer to strain the liquid in and out of the container.
I bought some gallon and 2 gallon plastic food containers from Sam's club that I put the parts in.
Also the product will look bad but still has a lot of life.
You have to be patient, it's not like acid that reacts instantly.
Also clean the parts ahead of time get as much grease and grime off as posable. They also talk about adding water to the liquid if it evaporates. So if you start with a gallon and only have 3/4 left, add a 1/4 gallon of water to rejuvenate it.