I have tried it both ways and it seems to vairy with the time of the year and what you are cleaning. When the Blendco salesman was trying to sell me he told me they didn't use a low p/h product, there product works and they didn't need acid to clean a car. Its all what works for you. If you have a good chemical distributor they should know what works in your area and help you set it up properly. Thats what they get the big bucks for, your paying for the knowledge they have.