Because of the influence of salts on enzymatic reactions, Qiagen extractions can be purified before making RAD tags. First, it is necessary to perform a chloropane extraction (phenol \/ chloroform 50\/50) by adding SDS to the aqueous phase (final conc. 0.1%), this eliminates contaminants introduced by the matrix of the column. Then, perform an ethanol precipitation followed by a wash with 70% ethanol. This is to eliminate the salt that was used to bind the nucleic acids to the column and also to remove EDTA (inhibitor!) which is 0.5 mM in the buffer AE. Eluting with water is nonsense as the pH is not optimal and thus yield is poor and the DNA is not buffered and there is always too much salt.