question about chaeto

[Nap]

I picked up some chaeto and it was the standard dark curly mass of algae. After a week in my sump the new growth is long and stringy and lighter in color. The growth rate is excellent but I am curious as to the reason behind such distinctly different growth pattern. Any ideas?
-Ian

 

[LockeOak]

I find it grows faster if you pull apart the clumps a bit and not let it get too dense, so that each filament gets enough light and water movement. It gets lighter when it's under stronger light, I assume because it needs less chlorophyll to produce enough photosynthate. So if it grows filaments that are more exposed to light they'll be lighter in color.