horizontal electrophoresis - glycerol or ficoll or without (Oct/20/2006 )

I haven't try out this yet but I appreciate very much of everyone's opinions and experiences. Do you think I should add glycerol to the loading buffer if I am to do horizontal agarose electrophoresis? I met someone who said they don't. Please advice.

I would add ficoll in preference to glycerol. Ficoll is said to be more resistent to bacteria growth. However, I know for a fact that bacteria will grow in Ficoll too.. So I keep my autoclaved ficoll loading buffer, in 1ml aliquote and frozen when not in use.