Well, that's a part of the original FASA tek. Because DMT Citrate is soluble in acetone, and DMT Fumarate is not, any time some DMT Citrate is converted to Fumarate (which it will to maintain equilibrium), the DMT Fumarate precipitates out, reducing the equilibrium back to zero on the fumarate side and ensuring that slowly but surely (almost) all the citrate crashes out as fumarate. Of course I don't know this first hand but I trust this forum