Algae question for Thom (if I may)

[Bill Wu <bwu at ualberta_ca>]

Hi Thom,

It's been great to read your input about planted aquariums.  Thanks for 
your time.  I don't have problems with BGA, hair algae or beard algae in my 
tanks except the little green spot algae on the glass and some rocks here 
and there.  The plants are doing well (pottery clay balls, PMDD and yeast 
CO2) .  Is there a general condition or cause that favor these little spot 
algae to grow?  Or is it just the way of life and I should just keep 
scraping the glass every week?  It would be nice if I can tweak the tanks 
closer to optimal condition.  I appreciate any suggestion.  =)

Thanks,
Bill Wu