Cameron, I purify my sequence reactions by ethanol precipitation, adding 1/10th vol sodium acetate (3M, pH 5.5) + 2.5 vols ethanol, both at room temp. After mixing, leave on ice for no longer than 10mins - I have found large dye blobs result if samples are left for longer than 10mins or if too much ethanol has been added. I hope this of some help. Susie