Dark period for plants

I forgot who mentioned this idea but...
As an experiment to see how it would affect a green algae bloom,
I turned off all the aquarium lights on both aquariums last Friday.
They will come back on again today which makes for 4 completely
dark days.

It doesn't seem to have changed the turbidity of the water in
the affected tank; it may have changed from green to gray but
I will see when I get home tonight.

The response of the plants has been very interesting:
many of the plant types grew quite a lot although the new leaves
tend to be paler in color esp those with dark or red pigments.

The older leaves on the Echinodorus cordifolius have turned
yellow. I believe this is the plant desperately sending all of
its vital reserves to the most vigorous and high growing leaves.

Brush algae (or any other algaes) did not grow at all during
this time. Hard to tell if they receded any.