While we're off topic... if it is a diatom problem try a half dose of erythromycin ( available as Maracyn ). It will clear up bacterial diatoms quickly. After that it's just a maintenance issue and keeping the 'trates as low as possible.
Nope, no diatoms. I went through that initially for about 6 months or so and right after those disappeared I was stuck with GDA. I didn't know what it was at first so I was constantly scraping it off. Now I know why it kept coming back...