OK Guys,
I have a book called The Marine Aquarium Problem Solver. By Nick Dakin..If anyone has this, on page 46, under Water Circulation, Under the Q & A section,,Quote
"Should the flow pattern be altered at night?"
Answer is "Yes, Most Corals and fish go into a resting mode in the dark, and calm conditions are appreciated."
Some circulatory pumps can be switched off altogether, connecting them to the lighting circuit is a good idea..
I dont know how they "Know" this, but just FYI, this is what it says..
~Susie