agarose gel melted after 4h running.. - (Feb/07/2007 )
I think i prepared the EDTA a year ago. It's store in schott bottle, there were no crystallization or contamination.
I run the gel with only a tank connected to the power supply, and it was ok. I think mdfenko is correct. It was caused by unequal distribution of power.
Thank you for solving my problem.
What I've also seen happening is that people didn't use enough buffer, so that when some of it evaporates (the longer your run, the more evaporation, the higher your current the more evaporation), the gel isn't completely covered anymore, and then it tends to start melting/degrading as well...