Stain in electrophoresis is going from + to - - (May/22/2013 )

Hey, I have small problem during DNA electrophoresis.
I am using Serva Dna Stain G. So I have to run gel quite long because I have 2 framgents (one is much bigger than the other one) but when I am running a gel (1%) after 45 min at 75V the stain is going up (like almost to half of it) so then I can't see any bands below. So I the stain is negativly charged.
As I remember with EtBr I have not such a problems? Or my memory is messing?

So the only think that I can try is post-staning? Or there is something else?
of course I can also do a extremely long gel

You should be able to add some stain to the running buffer.

with what concentration? The same as in the gel? but it is little bit wasting of stain.
Just for curious with EtBr is the same problem?
and how good is post staining?

EtBr has the same problem. Either stain after running the gel, or add stain to the buffer at the positive electrode.