Too much ? Algae


I found some brush and green spot algae growing on some of 
the tall Echinodorus Maior about the upper water. Is this a 
case of too much light, too much nutrient, lack of CO2 or 
what? I have 80W of lighting for 50gal tank, tetra cyrpto 
tablet every two weeks, tetra flora pride weekly during 
water change and CO2 yeast method. I've been following the 
same regimen for the last few months with relatively good 
plant growth and only have those algae on my slow growing 
Aglaodorum Griffithii. OK, I miss feeding the tablets once 
and have my E.Maior deformed for that time. Did I notice the 
algae start growing after that episode? Maybe! but not quite 

I'm going to try lowering my bulbs by an inch and fit some 
sort of mirror-like reflector to the lighting. Also try the 
noon-thunderstorm method. Any other suggestion?