Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocalWhy only Alexa dyes? I had very good results with Cy3 from Jackson
Immunochemicals (no com. interest) which has about 75% of maximum with
543-laser. If you nevertheless have to use Alexa, I would prefer 555.
Best
Florian