I am having trouble with my gels....so until recently we used EtBr when casting a gel. We make a large (200 well split over four rows) 1% gel with 1xTAE. When using the EtBr the ladder came out crystal clear. We have recently switched to SybrGreen1 Gel stain and now the ladder is just a smeared mess. I read that we could used the same volume of SybrGreen as EtBr which I did at first but it was a mess. I have sincce tried various smaller volumes with a very minor improvement. Others have this trouble too and I have done a gel with Etbr since to check and it was fine so I don't think it is the gel. The ladder was originally an older one but we have also had the same problem with a new one. The bands of DNA all come out fine so I am wondering if the Sybr Green is a lot more sensitive and the ladder wells are just over loaded? I tried reducing the amount of ladder per well which also hasn't really made a difference. Should I be diluting the ladder or something?