Hi Ivan

From what I’ve read, a quarter of an hour every hour during daylight, then a quarter of an hour every two hours during the night is sufficient (as you will get less evaporation in the evening).

But… its all going to be dependant on the size of your system, how effective your pump system is and also what the needs of your plants are going to be.

Every persons window farm is its own unique ecosystem…. you’ll need to get started and fine tune the needs or yours.

Good luck