I do let my pumps come on and off for 24 hours even though they don't need to be watered at night
because the plants can't utilize the
nutrient solution without photosynthesis from the sun or your grow
lights.
The reason I leave them on is when I use timers I forget to reset them when they get out of time
when we have periodic power outages.
The best solution would be to use a photo sensor to turn the pumps on automatically when the lights
come on or when the sun comes up. I will put that on my list of online projects.
Ron