The big argument is that you'll get a conductivity difference between
the two sides--as the gel runs, more ions acumulate on the negative (?)
side of the box and your gel will run funny.
I never recirc my buffer, even for long runs (3+ hours). Some will
argue that for Northerns you have to, but I never do that either.
Dept. Molecular Virology
Rockville, MD 20852
CANTOLUPO at GENVEC.COM