can some one explain to me pls what are the factors in the type of algae you
get in a tank?

for instance, I have brown spot algae and I really would prefer green hair
algae. what do I have to change to do this.

I have a 125g tank set at 25 degrees C. 40 watt "daylight" fluro. I also
have a fair amount of indirect sunlight if I open the curtains.
the java fern, java moss and corkscrew plant are doing fine. normal levels
of nitrate.