I run a lower/calmer % block at night simply because after spending a lot of time on the water (boating/fishing) I've noticed things typically are calmer at night. Wind from the day's heat dies down, as the temperature drops and between midnight and sunrise the surface water can be like glass. As the day heats up and wind kicks in things get choppy and so does my pump schedule. The current itself may not change but the upper part of the water column sure does and I think most of our coral lives in this zone. Of course weather, wind against the tide (from weather I guess lol), the moon cycle, etc all become factors and can chop things up. I'm also going from my neck of the woods (in the summer) experiences but I had to start somewhere . AI has the moon cycle for the lights...maybe someday they'll tie it into the pumps to be used somehow...might be neat!