As far as Blaser is concerned, they use Calcium Acetate (powder form) as an anti-foam agent. One con against this type of foam control is that the powder does not always dissolve properly in the coolant and it tends to cake the coolant sump pumps/holding tanks, and over time, will harden like cement. Hangsterfer's has another approach as far as controlling foam, as do other producers, such as Cincinnati and Master Chemical, to name just a couple.