i mix my own fuel, just castor oil and methanol, i also hardmount all of my tanks, my fuel never foams (or if it does its not a problem at all) so the "antifoaming agents" manufacturs put in their fuels solve a problem that isnt their (or they just dont put anyhting in the fuel to begin with)

either way if your fuel is foaming you have a bigger problem than foamy fuel....maybe a out of balance engine or something.....or you just have a huge engine that shakes your plane like crazy