I’ve been running the Kessil A80 light for 6 hours per day on the maximum intensity. The aquarium looks nice either with the lights on or lights off so here are some contrasting photos.
With the lights on, the fish tend to stay at the bottom of the tank. With the lights off they are considerably more adventuresome and happily explore the upper reaches. They have also come to expect that shortly after the light turns off in the evening that it will soon be feeding time and eagerly start congregating at the top (and following me around) in anticipation but in this “lights off” photo they have already been fed.
I also recently changed the flow pattern by moving the powerhead so the flow goes across the width of the tank from right to left rather than from the back to the front so the ludwigia isn’t drawn in, and put the powerhead back down to a lower level which reduces the amount of shimmer considerably. The fish always take a little while to adjust to a new flow pattern but it doesn’t take them long to figure it out. With less disruption of the water surface in an open-top tank you might expect increased levels of CO2 retained in the water column, but with this closed lid aquarium there doesn’t seem to have been any noticeable effect.