If you run your gel at a lower voltage for a longer time I would expect your bands to separate better. Also make sure that the gel has had plenty of time to cool down and set firmly. What percentage gel are you using and what type and concentration of buffer.What voltage and current are you running the gel at?

im using Agarose 1.5% and 1x TBE buffer and run at 100 volt but always all types of ladders ( different brands) always all bands over the 500bp are adhered tolgether and the PCR product thick and bended .

As this always occurs , i thought that the problem may be in the red safe

Thanks for your kid support

im using Agarose 1.5% and 1x TBE buffer and run at 100 volt but always all types of ladders ( different brands) always all bands over the 500bp are adhered tolgether and the PCR product thick and bended .

As this always occurs , i thought that the problem may be in the red safe

Thanks for your kid support

It is hard to say but I think that most of the problems could be caused by other factors than the dye.

I would run a 1% gel with the thinnest comb possible and run less sample ( I think that some of the smearing effects are overloading and too much salt in the sample. Run the gel slower and try heating the size standard to about 80c for a few seconds and cooling before loading in case some of the bands in the standard are annealing with each other but I think that the poor separation of the larger bands may be due to running too quickly. I attach a very good information sheet on agarose gels and you may find some of the images at the end interesting Also only cover the gel with 1-2 mm of depth of buffer as having too much buffer can cause distortions in the bands

thanks for your kind help. khaled